Stonv^  AETlcultural  College 

Cost 

PRESENTED  BY 


DEPARTMENT   OF   THE   INTERIOR 


MONOGRAPHS 


IGNITED  States  Geological  Survey 


VOLUME    XXXIY 


WASHINGTON 

GOYBRNMENT    PRINTING    OFFICE 

1899 


^^^^ 


UNITED  STATES  GEOLOGICAL  SURVEY 

CHAKLES   D.  WALCOTT,  DIRECTOK 


THE 


GLACIAL  GRAVELS  OF  MAINE 


THEIR  ASSOCIATED  DEPOSITS 


GEOKGE    H.   STONE 


'1    ^ 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1899 


Digitized  by  the  Internet  Archive 

in  2009  with  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/glacialgravelsofOOston 


CONTENTS. 


Letter  of  transmittal xiii 

Chapter  I. — Introduction 1 

Chapter  II. — Fundamental  facts  of  surface  geology  as  illustrated  in  Maine 5 

Surface  features  of  Maine 5 

Nature  of  the  rocks  of  Maine - 6 

Condition  of  rock  in  place 7 

Weathering 8 

Transportation  and  the  drift  agencies 10 

Transportation  by  landslip  and  soil-cap  movement 10 

Transportation  by  wind 11 

Transportation  by  running  water 13 

Sedimentation 15 

Transportation  and  erosion  by  springs  and  subterranean  streams 18 

Transportation  by  glaciers 20 

Transportation  by  floating  ice 21 

Shapes  of  drift  fragments 22 

Chapter  III. — Preliminary  descffiption  of  the  superficial  deposits  of  Maine 27 

Preglacial  deposits 27 

Glacial  deposits 29 

The  till 29 

Distribution  of  the  till 31 

The  upper  and  lower  till 33 

Sediments  transported  by  glacial  streams 34 

Marine  deposits  and  geological  work  of  the  sea 41 

Beach  and  cove  gravels 41 

Fossils  in  the  raised  beaches 53 

Sands  and  clays 54 

The  lower  clays — deltas  deposited  by  glacial  streams 55 

The  upper  clays — deltas  deposited  by  ordinary  rivers 56 

Summary 58 

Valley  drift 58 

River  terraces 61 

Recent  erosion  of  the  valley  alluvium  and  of  the  glacial  sands  and  gravels 63 

Origin  of  the  higher  river  terraces  of  the  valley  drift 67 

Summary 68 

Chapter  IV. — General  description  of  the  systems  of  glacial  gravels 70 

Vanceboro  system _ 70 

Dyer  Plantation  system _ 72 

Baring-Pembroke  system 73 

Houlton-Dennysville  system 73 

New  Limerick- Amity  branch : 80 

Smyrna-Dauforth  branch 80 

Island  Falls  branch 84 

Local  kames  in  Marion 85 

East  Machias  system 83 

Crawford  system 86 

Wilderness  region  north  of  Columbia,  Columbia  Falls,  and  Jonesboro 88 

Wesley-Northfield  system 90 

Topsfield-Old  Stream  system 90 

Grand  Lake  osar , 92 

Farm  Cove  gravels ■_ 92 


yj  •      Co^^TENTS. 

Chapter  IV.— General  description  of  the  systems  of  glacial  gravels— Continued.  Page. 

Bancroft-Grand  Lake  system 93 

Sisladobsis-Pleasant  River  system 91 

Seboois-Kingman-Columbia  system 95 

Winn-Lee  gravels ^^^ 


Katahdin  system  . 


104 


Staceyville-Medway  branch 1^5 

Salmon  Stream  branch 11° 

Sam  Avers  Stream  branch Ho 

Milinoket  Lake-Howland  branch 116 

Soper  Brook  gravels H ' 

Note  on  the  upper  Penobscot  Valley H'^ 

Eastbrook-Sullivan  system - H ' 

Minor  gravel  series H ' 

North  Maria ville  system H^ 

West  Mariaville  massive 11° 

Peaked  Mountain  eskers 119 

Clifton-Lamoine  system 119 

Local  eskers  northwest  of  Ellsworth 1-1 

Holden-Orland  system 1-1 

Moosehead  Lake  system l'^- 

Medford-Hampdeu  osar 122 

Moosehead  Lake  osar I-"' 

Keuduskeag-Hampden  branch 131 

Exeter  Mills-Carmel  branch - 133 


Jo  Merry  osar  . 


134 


Roach  River  osar 131 

Katahdin  Iron  Works  osar 131 

Lilly  Bay-Willimantio  osar 13-t 

Etna-Monroe  system 135 

Local  eskers  in  Jackson - -  138 

Waldo-Belfast  Bay  system --  138 

Brooks-Belfast  system 138 

Local  eskers  in  Dexter 139 

Corinna-Dixmont  system 139 

East  Troy  kames 112 

Troy-Belfast  system 113 

Morrill-Belfast  Bay  system - HI 

General  note  on  the  Belfast  region -  -  115 

Local  eskers  in  Troy  and  Plymouth 1-15 

Georges  River  system H''' 

Hartland-Montville  system 118 

Summary 156 

Cambridge-Harmony  gravels 159 

Palermo- Warren  system 160 

Short  eskers  in  Waldoboro 163 

Medomac  Valley  system - 163 

Local  gravels  in  Nobleboro  and  Jefferson 163 

Dyers  River  system 161 

South  Albion-China  system 16o 

Clinton- Alna  system 168 

Albion  branch 169 

Winslow-AViudsor  branch 169 

Lower  Kennebec  Valley  system 1"1 

Short  eskers  south  and  southwest  of  Moosehead  Lake 173 

Local  eskers  iu  Richmond  and  Bowdoinham 1"3 

Sedimentary  drift  of  the  upper  Kennebec  Valley lT-1 


CONTENTS.  YJI 

Chapter  IV. — General  description  of  the  systems  of  glacial  gravels — Continued.  Page. 

Anson-Madison  series 179 

Norridgewock-Belgrade  system 181 

Nortli  Pond  branch 184 

Mercer-Belgrade  branch 184 

Late  glacial  history  of  the  upper  Kennebec  Valley 185 

Short  eskers  in  Manchester  and  Litchfield 186 

Litchfield-Bowdoin  system 186 

Local  eskers  in  northwestern  Maine , 187 

Dead  River- Jerusalem  system 187 

Note  on  the  northwestern  part  of  Maine 188 

Eeadfield-Brunswick  system 189 

Wayne-Monmouth  branch 193 

Gravels  near  Sabatis  Pond 195 

Mount  Vernon  esker 195 

Chesterville-Leeds  system ■■. 196 

Freeport  system 200 

Lewiston-Durham  series 201 

Hillside  eskers  in  Jay  and  Wilton 205 

Canton- Auburn  system 206 

Note  on  the  Androscoggin  Valley , 210 

Hillside  eskers  in  Hartford 210 

Peru-Buckfield  system 211 

West  .Summer-Poland  system 213 

Branches  in  Hebron  and  near  West  Minot 214 

Hillside  eskers  in  Oxford  County 215 

Yarmouth-Cape  Elizabeth  system 215 

Androscoggin  Lakes-Portland  system 216 

Kennebago  kames 233 

Lockes  Mills  branch 233 

General  note  on  the  Portland  system 23^ 

Local  eskers  in  Westbrook 235 

Casco- Windham  system 235 

Gray-North  Windham  series 238 

General  note  on  the  glacial  gravels  of  southwestern  Maine 238 

Note  on  the  basin  of  Sebago  Lake 239 

Naples-Standish  series 240 

Sebago  series 244 

Bridgton- Baldwin  series _ 244 

Tributary  branches 246 

Delta  branches 246 

Albany  Saoo  River  series 248 

Delta  branch  at  North  Waterford 252 

Alluvial  terraces  of  the  Saco  River 255 

Great  complex  of  northwestern  York  and  southwestern  Oxford  counties 256 

Acton-North  Berwick  system 262 

Lebanon  system 263 

West  Lebanon  system 263 

Chapter  V. — Classification  and  genesis 264 

Preglacial  land  surface  and  soils 265 

Greenland  snow  and  ice 269 

The  till 270 

Morainal  debris  of  the  ice-sheet 272 

Moraine  stuff  the  lower  iiart  of  the  ice 272 

Waldoboro  moraine 272 

Moraines  of  Audroscoggiu  glacier 274 

Quantity  of  englacial  debris 275 


VIII  CONTENTS. 

Chapter  V. — Classification  and  genesis — Continued.  Page> 
The  till — Continued. 

Ground  moraine 277 

Drumlins 280 

Relation  to  marine  gravels 282 

Bowlder  fields  and  trains 284 

Was  there  more  than  one  glaciation  of  Maine  ? 284 

Glacial  sediments 291 

Relation  of  water  to  the  glacier 291 

Sizes  of  the  glacial  rivers  of  Maine 292 

Zones  of  the  Maine  ice-sheet 294 

Englacial  streams :.  296- 

Directions  of  subglacial  and  englacial  streams  under  existing  glaciers 297 

Internal  temperatures  of  ice-sheets 302 

Basal  waters  of  ice-sheets 30.5 

Basal  furrows  as  stream  tunnels 308 

Genesis  and  maintenance  of  subglacial  and  englacial  channels 310 

Forms  of  glacial  channels 316 

Extraordinary  enlargements  of  the  glacial  river  channels 317 

Directions  of  glacial  rivers  compared  with  the  flow  of  the  ice 319 

Relations  of  glacial  rivers  to  relief  forms  of  the  land 321 

Sedimentation  in  places  favorable  or  unfavorable  to  the  formation  of  crevasses 323 

Glacial  rivers  of  Maine :  Summary 324 

Glacial  potholes 324 

Formation  of  kames  and  osars _ 330 

Bowlders  of  the  glacial  gravels 333 

Remarks  on  the  glaciation  of  the  Rocky  Mountains 338 

La  Plata  Mountains 338 

Las  Animas  Valley 340 

Upper  Rio  Grande  Valley 343 

Valley  of  the  San  Miguel  River 343 

Valley  of  the  Uncompahgre  River 344 

Upper  Artausas  Valley 345 

Pikes  Peak  Range 348 

South  Park 349 

Roaring  Fork 349 

Rock  Creek 350- 

Estes  Park ^ 350 

Valley  of  the  Salmon  River,  Idaho 351 

Moraines 352 

Glacial  gravels 353- 

Summary 354 

General  summary  of  the  Rocky  Mountain  region 354 

Glaciers  of  Alaska 355 

Overwash  aprons 356 

Osar  streams  and  osars 356 

Chapter  VI. — Classification  of  the  glacial  sediments  of  Maine 359 

Preliminary  remarks 359' 

Names 359 

Glacial  gravels  as  modified  by  the  sea 360 

Short  isolated  osars  or  eskers 361 

Hillside  osars  or  eskers 364 

Isolated  kames  or  short  eskers  ending  in  marine  deltas 368- 

Isolated  osar-mounds  or  massives  not  ending  in  marine  deltas  proper 369 

Glacial  marine  deltas 37L 


CONTENTS.  IX: 

Chaptkr  VI. — Cliissitication  of  the  glacial  sediuients  of  Maine — Continued.  Page. 

Systems  of  iliscontinuous  osars 37& 

Glacial  gravels  of  the  coastal  region 379 

Relations  of  glacial  giiavels  ts  the  fossiliferous  marine  beds 379' 

Lenticular  shape  of  the  coastal  gravel  masses 382 

Decrease  of  glacial  gravels  toward  the  coast 386 

Summary - 389 

Retreatal  phenomena 390 

Causes  of  noncoutiuuous  sedimentation  within  ice  channels 395 

R^sumiS :  History  of  the  coastal  gravels 403 

Late  glacial  history  of  the  coastal  region 409 

Summary 411 

Gears 413 

Comparison  of  continuous  with  discontinuous  osars 416 

Were  osars  deposited  by  subglacial  or  by  superficial  streams  ? 420 

Length  of  ridge 421 

Angle  of  lateral  slope  of  the  ridges 423'' 

Internal  structure 423 

Meanderings  of  a  ridge 425 

Pinnacles  or  elongated  cones 426' 

Broad  and  massive  enlargements 427 

Reticulated  ridges 427 

Probable  velocities  of  the  two  kinds  of  streams 428 

Erosion  of  the  ground  moraine 429 

Gaps  in  the  osars 430 

Size  of  the  osars 431 

Local  versus  far- traveled  material 431 

Phenomena  of  glacial  rivers  in  crossing  hills  and  valleys 433 

Broad  osars  or  osar  terraces 440 

Formation  of  the  broad  osar  channels 444 

Reticulated  eskers  or  kames 448 

Ways  in  which  a  ridge  of  aqueous  sediment  can  be  formed 451 

Formation  of  kettleholes  and  other  basins  inclosed  by  ridges  or  by  plains  of  aqueous 

sediments 453 

Origin  of  the  glacial  gravel  complex  and  its  relation  to  marine  and  lacustral  deltas 455 

Plexus  situated  at  one  end  of  a  marine  glacial  delta 455 

Reticulated  ridges  at  the  proximal  ends  of  the  glacial  lacustrine  deltas 459' 

Reticulated  ridges  as  a  part  of  glacial  lacustrine  massives 459' 

Reticulated  ridges  within  ice  channels 460 

Origin  of  the  larger  complexes 463 

Osar  border  clay 468 

Deltas  deposited  by  glacial  streams  in  frontal  glacial  lakes 469 

Valley  drift 470 

Valley  drift  of  purely  fluviatile  origin 470 

Valley  drift  of  semiglacial  origin 474 

Relation  of  the  valley  drift  to  the  other  glacial  and  marine  sediments 475 

Historical  relations 476 

Relation  of  the  valley  drift  to  the  marine  beds 480' 

Former  height  of  the  sea 481 

Causes  of  the  relative  fineness  of  the  lower  strata  of  the  valley  drift  and  the  marine 

beds  of  the  interior  valleys 485 

The  lower  stratum,  composed  of  clay,  silt,  or  fine  sand 485 

The  coarser  upper  stratum 486 

Sizes  of  the  valley-dri rt  rivers 488' 

Index 491 


ILLUSTRATIONS, 


Page. 

Plate     I.  Hummock  of  granitic  till ;  Casco 34 

II.  Preliminary  map  of  marine  clays  of  Maine 58 

III.  ^,  Lakelet  surrounded  by  glacial  gravel ;  Lee 104 

B,  Dome  of  coarse  gravel ;  Springfield - 104 

IV.  A,  Osar  crossing  Penobscot  Kiver 106 

B,  Osar  expanded  to  a  plain;  Soutb  Lincoln 106 

V.  A,  Osar  forking  into  a  double  ridge 108 

B,  Katalidin  osar;  Enfield 108 

VI.  A,  High  gravel  massive 112 

B,  Till  bowlders  in  glacial  gravel 112 

VII.  A,  Osar  penetrating  alow  pass;  Clifton 120 

B,  Broad  osar  terrace ;  Bucksport 120 

VIII.  Osar  ending  at  the  shore  of  Penobscot  Bay ;  Stockton 130 

IX.  Meandering  of  osar;  Detroit 1*6 

X.  Hogback  Mountain,  looking  west  across  south  end  of  pass - 152 

■  XI.  Diverging  delta  branches  of  osar;  Hogback  Mountain  Pass 154 

XII.  Lenticular  gravel  hillock ;  China 168 

XIII.  Succession  of  three  lenticular  eskers,  part  of  a  discontinuous  osar ;  Windsor 170 

XIV.  A,  Funnel  iu  gravel  massive ;  West  Bo wdoin 186 

B,  Ravines  in  gravel  parallel  with  the  direction  of  the  glacial  river;  Durham 186 

XV.  A,  South  end  of  a  hillside  esker ;  Jay 214 

B,  Hillside  esker ;  Hebron 214 

XVI.  Broad  osar  penetrating  a  low  pass ;  Woodstock 220 

XVIX.  Osar  eroded  by  Sebago  Lake - 242 

XVIII.  Broad  osar  passing  over  high  hill ;  Baldwin .244 

XIX.  Till  bowlders  in  osar;  Baldwin 246 

XX.  Broad  osar  crossing  col;  Brownfield 254 

XXI.  The  Notch;  Hiram 258 

XXII.  Osars  on  hillsides ;  Newfield ^ 260 

XXIII.  A,  Plexus  of  kame  ridges  and  monnds  near  North  Acton 262 

B,  Terminal  moraine ;  Winslows  Mills,  Waldoboro 262 

XXIV.  A,  Section  of  terminal  moraine 272 

B,  Top  of  terminal  moraine 272 

XXV.  A,  Terminal  moraine ;  Waldoboro 274 

B,  Terminal  moraine  of  Androscoggin  glacier ;  Gilead 274 

XXVI.  A,  Bare  ledges  in  channel  of  glacial  river ;  Parsousfield 332 

B,  Osar  sprinkled  with  till  bowlders;  Prospect 332 

XXVII.  A,  Reticulated  ridges  of  coarse  water-rolled  gravel;  Parsousfield 336 

B,  Stratification  of  glacial  marine  delta ;  Monroe 336 

XXVIII.  Discontinuous  osar  near  Monroe  Village 376 

XXIX.  Till  bowlder  on  glacial  gravel ;  West  Bowdoin 378 

XXX.  Till  bowlders  on  marine  delta  gravel ;  Waterboro 3-2 

XXXI.  Map  of  Maine,  showing  approximately  the  lines  of  frontal  retreat  of  the  ice 392 

XXXII.  Osar,  Whalesback;  Aurora *1* 

XXXin.  Wall  on  broad  osar ;  Woodstock *'t2 

XXXIV.  Reticulated  kames;  Porter *^8 

XXXV.  Large  osar  bowlders  on  hillside  ridge ;  Porter 450 

XXXVI.  A,  Kettlehole  in  marine  delta,  near  Monroe  Village 452 

B,  Lake  bordered  on  all  sides  by  terraces  of  glacial  gravel ;  Hiram 452 


XII  ILLUSTRATIONS. 

Page 
Plate  XXXVII.  A,  Basin  containing  lakelet  in  the  midst  of  a  broad  gravel  plain;  northern 

part  of  Windsor *54 

B,  Gravel  mesa ;  southern  part  of  China 154 

XXXVIII.  Map  of  Androscoggin  County,  showing  location  of  glacial  gravels 490 

XXXIX.  Map  of  Aroostoot  County,  showing  location  of  glacial  gravels 490 

XL.  Map  of  Cumberland  County,  showing  location  of  glacial  gravels 490 

XLI.  Map  of  Franklin  County,  showing  location  of  glacial  gravels 490 

XLII.  Map  of  Hancock  County,  showing  location  of  glacial  gravels 490 

XLIII.  Map  of  Kennebec  County,  showing  location  of  glacial  gravels 490 

XLIV.  Map  of  Knox  County,  showing  location  of  glacial  gravels 490 

XLV.  Map  of  Lincoln  and  Sagadahoc  counties,  showing  location  of  glacial  gravels..  490 

XLVI.  Map  of  Oxford  County,  showing  location  of  glacial  gravels 490 

XLVII.  Map  of  Penobscot  County,  showing  location  of  glacial  gravels 490 

XL VIII.  Map  of  Piscataquis  County,  showing  location  of  glacial  gravels 490 

XLIX.  Map  of  Somerset  Couuty,  showing  location  of  glacial  gravels 490 

L.  Map  of  Waldo.  County,  showing  location  of  glacial  gravels 490 

LI.  Map  of  Washington  County,  showing  location  of  glacial  gravels 490 

LII.  Map  of  York  County,  showing  location  of  glacial  gravels 490 

Fig.  1.  Stratification  of  wind-blown  sand ;  Lockes  Mills 12 

2.  Section  across  deep  lenticular  sheet  of  till ;  Rents  Hill,  Readfield 32 

3.  Section  across  Munjoy  Hill,  Portland 3-" 


4.  Longitudinal  section  of  cove. 


42 

5.  Transverse  section  of  sea  wall *_ 

6.  Transverse  section  of  ancient  cove  gravels '^^ 

7.  Ancient  beaches  sloping  up  from  the  shore '^^ 

8.  Section  across  terminal  moraine  near  head  of  Kennebec  Inlet 51 

9.  Osar  and  delta-plain  inclosing  lakelet ;  Vanceboro ^l 

10.  Osar  cut  by  the  Piscataquis  River  at  Medford  Ferry 123 

11.  Section  of  osar ;  Levant 1^-' 

jcrumpled  strata  near  surface  of  osar ;  Kenduskeag  Valley 13- 

14.  Section  across  Exeter  Mills-Hermon  osar,  in  Carmel 133 

15.  Meandering  of  osar ;  Carmel 133 

16.  Osar;  Pittsfield 1^^ 

17.  Map  of  Hogback  Mountain ;  Montville  and  vicinity 151 

18.  Section  across  channel  eroded  in  the  till ;  Montville 152 

19.  Reticulated  ridges  and  Hogback  Mountain,  from  the  north 153 

20.  Section  across  Kennebec  Valley 1'" 


21.' 


Stratification  of  a  lenticular  esker;  Auburn. 


[204 


i-t'^rratincaTjiuu  ui  a  icmjiuuiiiL  coii-ci. ,  xxLik/uiu .... — —  — . 1205 

23.  Landslip  at  Bramhall  Hill;  Portland 232 

24.  Broad  osar  penetrating  narrow  pass  over  hill  400  feet  high ;  Limington 258 

25.  Ideal  sections  across  channels  of  superficial  glacial  streams 317 

26.  Section  of  clifif  and  pothole ;  Paris 328 

27.  Sheet  of  marine  clay  overlying  osar ;  Waterville 379 

28.  Marine   clay  overlying  base  of  osar  and  itself  covered  with   a  capping  of  gravel; 

Corinth 380 

29.  Marine  clay  in  the  midst  of  osar  gravel ;  Hermon  Pond 380 

30.  Marine  clay  overlying  base  of  osar ;  Hampden 381 

31.  Lenticular  esker  flanked  with  blowing  marine  sand ;  Bowdoin 383 

32.  Ideal  section  of  glacial-stream  channels  crossing  transverse  valleys 433 

33.  Section  of  valley  between  Sherman  and  Springfield -^37 

34.  Diagrammatic  section  across  osar-plain ;  Woodstock  and  Milton <142 

35.  Diagrammatic  section  across  osar-plain ;  valley  of  Bog  Brook,  Canton 442 

36.  Diagram  illustrating  the  method  of  finding  the  highest  sea  level  in  an  interior  valley  . .  482 


LETTER  OF  TRANSMITTAL. 


University  of  Chicago, 

Chicago,  June  13,  1894. 
Sir:  I  have  the  pleasure  of  transmitting  a  report  by  Prof.  George  H. 
■Stone  on  The  Glacial  Gravels  of  Maine  and  their  Associated  Deposits. 

The  value  of  this  elaborate  report  upon  one  of  the  most  remarkable 
of  the  phenomena  connected  with  the  Ice  age  needs  no  comment  in  this 
■connection. 

Very  respectfully,  yours, 

T.   C  Chambeelin, 

Geologist  in  Charge. 
To  the  Director, 

United  States  Geological  Survey. 


THE  GLACIAL  GRAVELS  OF  MAINE  AND  THEIR 
ASSOCIATED  DEPOSITS. 


By  George  H.  Stone. 


CHAPTER   I. 
INTRODUCTION. 

This  iiivestig-atiou  was  begun  in  the  summer  of  1876,  and  has  been 
prosecuted  during  vacations.  The  report  was  substantially  completed  in 
June,  1889.  The  work  was  much  embarrassed  by  the  lack  of  sufficiently 
accurate  maps,  those  available  warranting  only  a  reconnaissance  and  an 
approximate  location  of  the  kames,  osars,  etc.,  in  relation  to  the  roads, 
streams,  and  other  features  shown.  The  true  relation  of  the  glacial  gravels 
to  the  relief  forms  of  the  land  can  be  shown  only  on  topographical  maps, 
and  the  full  delineation  of  the  magnificent  kame  and  osar  systems  of 
Maine  is  therefore  left  to  the  topographer  and  geologist  of  the  futiu-e. 
In  certain  parts  of  the  State,  especially  in  the  wooded  regions,  the  work 
is  not  complete,  but  it  can  be  confidently  claimed  that  all  the  longer 
systems  and  the  more  common  types  of  formation  are  here  described. 

The  investigation  made  slow  progress,  not  only  because  there  were 
several  thousand  miles  to  be  carefully  explored,  but  especially  because  the 
nature  of  the  subject  renders  such  an  investigation  exceedingly  difficult. 
The  scout  of  the  Western  frontier  who  undertakes  to  guide  a  body  of 
troops  in  pursuit  of  hostile  Indians — to  follow  the  trail,  and,  from  the  traces 
left  behind,  to  give  a  history  of  the  enemy's  performances  from  day  to 
day — has  a  difficult  task  before  him;  but  in  thus  reconstructing  history  he 
has  the  advantage  of  knowing,  from  direct  observation,  the  habits  of  the 
Indians.  In  his  study  of  glacial  deposits  the  glacialist  labors  under  the  dis- 
advantage of  not  knowing,  by  observation,  the  exact  nature  of  the  geolog- 
ical work  going  on  beneath  and  within  an  ice-sheet.     It  is  comparatively 

MON  XXXIV 1  1 


2  GLACIAL  GRAVELS  OF  MAIIS^E. 

easy  to  theorize  regarding  the  probable  behavior  of  such  a  bod)^  of  ice, 
and,  if  properlj^  held  in  check,  imagination  is  of  the  greatest  use  in  such 
an  investigation,  but  the  chances  for  error  are  very  great.  The  method 
here  adopted  has  been  to  collect  as  large  a  body  of  facts  as  possible,  and 
then  carefully  to  test  various  hypotheses  by  the  facts,  rejecting  or  holding 
in  abeyance  all  theories  not  supported  by  positive  field  evidence.  Glacial- 
ists  are  exploring  a  comparatively  untrodden  field,  and  it  behooves  them 
to  proceed  cautiously  and  to  avoid  dogmatism  and  denunciation. 

This  report  is  intended  to  apply  only  to  Maine,  and  is  not  a  histor}^  of 
the  progress  of  glacial  science.  For  present  purposes,  therefore,  it  is  not 
necessary  to  refer  in  detail  to  the  many  reports  and  ai-ticles  which  have 
been  written  on  the  subject  of  the  water-assorted  glacial  drift  of  North 
America. 

Chronological  list  oficorls  treating  of  the  glaciology  of  Maine. 

Bailey,  J.  W.    Accouut  of  an  excursion  to  Mount  Katalidin,  in  Maine.    Am.  Jour. 

Sci.,  1st  series,  vol.  32, 1837,  pp.  20-34.    Drift  phenomena,  pp.  26, 33-34. 
Jackson,  Charles  T.    First  report  on  the  geology  of  the  State  of  Maine.    Augusta, 
1837.    8°.    127  pp. 

Secoud  report  on  the  geology  of  the  State  of  Maine.    Augusta,  1838.    8°.    168  pp. 

Third  annual  report  on  the  geology  of  the  State  of  Maine.  Augusta,  1839.  8". 
Pp.  1-276,  i-lxiv. 

[Also  two  reports  on  the  geology  of  the  Wild  Lands  (1S39),  largely  duplicative 
of  the  above  works.] 

[Bowlders  and  diluvial  scratches  in  Maine.  Discussion.]  Am.  Jour.  Sci.,  1st  series, 
vol.  41, 1841,  p.  176. 

[Glacial  drift.]  Am.  Jour.  Sci.,  1st  series,  vol.  45, 1843,  i)p.  320-324.  Eeference  to 
drift  in  Maine. 
Hitchcock,  0.  H.  General  report  upon  the  geology  of  Maine.  In  sixth  annual 
report  of  the  secretary  of  the  Maine  board  of  agriculture  (Augusta,  1861,  8°), 
pp.  146-328.  Saperficial  deposits,  i)p.  257-288.  Includes  letter  from  John 
De  Laski  concerning  effects  of  glacial  action  on  Vinalhaven. 

Geology  of  the  Wild  Lands.  In  sixth  annual  report  of  the  secretary  of  the 
Maine  board  of  agriculture  (Augusta,  1861, 8°) ;  Part  II,  Physical  geography, 
agricultural  capabilities,  geology,  botany,  and  zoology  of  the  Wild  Lands  in 
the  northern  part  of  the  State,  pp.  331-458.  Geology,  pp.  377-442,  including 
remarks  on  glacial  drift.     Geological  map  opposite  p.  377. 

Geology  of  Maine.  In  seventh  annual  report  of  the  secretary  of  the  Maine 
board  of  agriculture  (Augusta,  1862,  8°) ;  Part  II,  Eeports  upon  the  geology 
cf  Maine,  pp.  223-430.  Surface  geology,  pp.  377-401.  Glacial  phenomena 
described,  pp.  378-391.  This  report  includes  a  letter  from  John  De  Laski  on 
"Ancient  glacial  action  in  the  southern  part  of  Maine,"  pp.  382-388. 


PUBLICATIONS.  3 

Holmes,  Ezekiel.  Geology  of  a  portion  of  Aroostook  County,  Maine.  In  seventh 
annual  report  of  the  secretaiy  of  the  Maine  board  of  agriculture  (Augusta, 
1862,  8°) ;  Part  II,  Eeports  upon  the  geology  of  Maine,  pp.  223-430.  Letter 
from  Dr.  Holmes  to  Prof.  C.  H.  Hitchcock,  geologist,  pp.  359-376.  Reference 
to  drift  phenomena. 

De  Laski,  John.  Ancient  glacial  action  in  Maine.  In  seventh  annual  report  of  the 
secretary  of  the  Maine  board  of  agriculture  (Augusta,  1862,  8°);  Part  II, 
Eeports  upon  the  geology  of  Maine,  pp.  223-430.  Letter  to  Prof.  C.  H.  Hitch- 
cock, geologist,  pp.  382-388.  Also  in  Am.  Jour.  Sci.,  2d  series,  vol.  36, 1863, 
pp.  274-276. 

De  Laski,  John.  Glacial  action  about  Penobscot  Bay.  Am.  Jour.  Sci.,  2d  series, 
vol.  37,  1864,  pp.  335-344. 

Packard,  A.  S.  Eesults  of  observations  on  the  drift  phenomena  of  Labrador  and 
the  Atlantic  coast  southward.  Am.  Jour.  Sci.,  2d  series,  vol.  41, 1866,  pp.  30-32. 
Maine,  pp.  31,32. 

Whittlesey,  Charles.  On  the  ice  movements  of  the  Glacial  era  in  the  valley  of  the 
St.  Lawrence.     Am  Ass.  Adv.  Sci.,  Proc,  vol.  15, 1866,  part  2,  pp.  43-54. 

Packard,  A.  S.  Observations  on  the  glacial  phenomena  of  Maine  and  Labrador. 
Mem.  Boston  Soc.  Nat.  Hist.,  vol.  1,  1866-1869.    4°.    Pp.  210-303,  pis.  7-8. 

Wells,  AValter.  Eeport  of  the  superintendent  of  the  hydrographic  survey  of  Maine. 
Augusta,  1869.    Tlje  water  power  of  Maine. 

Dana,  J.  D.  On  the  position  and  height  of  the  elevated  plateau  in  which  the  glacier 
of  New  England,  in  the  Glacial  era,  had  its  origin.  Am.  Jour.  Sci.,  3d  series 
vol.  2, 1871,  pp.  324-330.  ' 

De  Laski,  John.  Glacial  action  on  Mount  Katahdiu.  Am.  Jour.  Sci.,  3d  series  vol  3 
1872,  pp.  27-31.  ' 

Dana,  J.  D.  On  the  Glacial  and  Champlain  eras  in  New  England.  Am.  Jour.  Sci. 
3d  series,  vol.  5, 1873,  pp.  198-211,  217-218.     Maine,  205, 206,  210. 

Hitchcock,  O.  H.  The  geology  of  Portland,  Maine.  Proc.  Am.  Ass.  Adv.  Sci.,  vol. 
22, 1873,  pp.  163-175. 

Hitchcock,  C.  H.  (J.  H.  Huntington  and  Warren  Upham,  assistants).  Eeport  on  the 
geology  of  New  Hampshire  (Concord),  vol.  1,  1874;  vol.  2,  1877;  vol.  3,  1878. 
This  report  contains  much  Information  as  to  the  drift  of  the  western  border  of 
Maine  and  the  region  adjacent  thereto.  The  cha])ters  on  glacial  geology  are 
largely  by  Upham. 

Sherman,  Paul.     Glacial  fossils  in  Maine.     Am.  Naturalist,  vol.  7, 1873,  pp.  373-374. 

Shaler,  N.  S.  Eecent  changes  of  level  on  the  coast  of  Maine.  jMem.  Boston  Soc. 
Nat.  Hist,  vol.  2,  part  3,  No.  3.     Boston,  1874.    4°.     Pp.  321-340. 

Packard,  A.  S.  Glacial  marks  on  the  Pacific  and  Atlantic  coasts  compared.  Am. 
Naturalist,  vol.  11, 1877,  pp.  674-680. 

Huntington,  J.  W.  Geology  of  the  region  about  the  headwttters  of  the  Androscog- 
gin Elver,  Maine.  [Abstract.]  Proc.  Am.  Ass.  Adv.  Sci.,  vol.  26,  1877,  pii. 
277-286.     Glacial  drift,  pp.  284-285. 

Stone,  George  H.  The  kames  of  Maine.  [Abstract.]  Proc.  Boston  Soc.  Nat.  Hist., 
vol.  20, 1878-18S0  (Boston,  1881),  pp.  430-469. 

Wright,  G.  P.  The  kames  and  moraines  of  New  England.  Proc.  Boston  Soc.  Nat. 
Hist.,  vol.  20,  1878-1880,  pp.  210-220. 


4  GLACIAL  GEAVELS  OF  MAINE. 

Stone,  G.  H.     The  kames  or  eskers  of  Maine.     Proc.  Am.  Ass.  Adv.  Sci.,  vol.  29, 

1880,  pp.  510-519. 

Hamlin,  C.  E.  Observatious  upon  the  physical  geogi-aphy  and  geology  of  Mouut 
Katahdiu  and  the  adjacent  district.  Bull.  Mus.  Comp.  Zool.  Harvard  Coll.,  vol. 
7,  1880-1884,  pp.  189-223. 

Stone,  George  H.    Apparent  glacial  deposits  in  valley  drift.     Am.  Naturalist,  vol.  15, 

1881,  pp.  251-252. 

The  karae  rivers  of  Maine.     [Abstract.]     Science,  vol.  2,  1883,  p.  319. 

The  kame  rivers  of  Maine.  [Abstract.]  Proc.  Am.  Ass.  Adv.  Sci.,  vol.  32,  1883, 
pp.  231-237. 
Shaler,  N.  S.  The  geology  of  the  island  of  Mount  Desert,  Maine.  lu  Eighth 
Annual  Report  of  the  United  States  Geological  Survey,  1886-87,  J.  W.  Powell, 
Director,  Part  II  (Washington,  1889),  pp.  987-1061.  Surface  and  glacial  geol- 
ogy, pp.  994-1031,  with  map  of  surface  geology,  p.  1060. 

Many  briefer  articles  have  been  published  on  the  subject  of  the  Maine 
drift.  Notaljle  among  these  are  the  early  writings  of  Agassiz  on  the  glacial 
geology  of  New  England,  published  in  part  in  the  Atlantic  Monthly. 


CHAPTER   11. 

FUNDAMENTAL    FACTS    OF    SURFACE    GEOLOGY    AS 
ILLUSTRATED   IN   MAINE. 

In  order  that  there  may  be  no  doubt  as  to  the  sense  ui  which  certain 
words  are  employed  in  this  report,  or  as  to  the  standpoint  from  wliich  it  is 
written,  the  following  explanatory  chapter  is  prefixed  to  the  report  proper. 
This  is  the  more  necessary  becaiTse  I  have  found  it  desirable  to  use  some 
words  in  a  more  restricted  sense  than  that  in  which  they  have  been  used 
by  many  in  the  past. 

The  principal  facts  with  which  the  student  of  the  drift  has  to  deal  are 
the  following: 

SURFACE  FEATURES  OF  IHATNB. 

The  surface  featiu-es  of  the  regions  penetrated  by  the  several  systems 
of  glacial  gravel  will  be  described  in  connection  with  the  gravels.  It  is 
therefore  not  necessary  here  to  give  any  detailed  description  of  the  topo- 
graphical features  of  the  State.     A  few  remarks  will  suffice. 

The  State  consists  of  two  main  di-ainage  slopes :  (1)  That  drained 
southward  into  the  Gulf  of  Maine  by  the  Saco,  Presumpscot,  Androscogg'in, 
Kennebec,  Penobscot,  Narraguagus,  Machias,  and  St.  Croix  rivers,  and 
by  numerous  smaller  streams.  The  average  fall  of  the  streams  of  this 
slope  is  not  far  from  7  feet  per  mile.  All  the  larger  deposits  of  glacial 
gravel  appear  to  be  confined  to  this  slope.  (2)  That  drained  northward 
and  eastward  into  the  St.  John  River.  This  slope  contains  much  swampy 
and  other  rather  level  land,  with  here  and  there  hills  rising  above  the 
great  plain. 

An  inspection  of  the  river  systems  of  Maine  shows  great  irregularities 


6  GLACIAL  GRAVELS  OF  MAINE. 

of  surface.  In  the  absence  of  topographical  maps  these  surface  features 
can  be  described  only  approximately.  A  fact  of  great  significance  in  an 
investigation  of  the  drift  of  Maine  is  the  presence  of  numerous  ranges  of 
hills  rising  200  to  1,000  feet  above  the  country  to  the  north  of  them,  and — 
a  fact  still  more  significant — they  usually  were  more  or  less  transverse  to 
the  direction  of  glacial  flow.  Part  of  these  have  the  general  northeast 
Appalachian  direction,  others  lie  nearly  east  and  west.  During  the  time 
of  maximum  thickness  of  the  ice  the  glacier  flowed  up  and  over  these 
hills,  but  during  the  final  melting  these  ranges  stopped  the  flow  of  the 
ice  in  many  cases  and  confined  it  to  the  valleys  lying  north  of  them. 
The  behavior  of  the  glacial  rivers  with  respect  to  these  transverse 
hills  is  of  great  assistance  in  determining  the  character  of  the  rivers  and 
their  laws. 

Much  infoi'mation  regarding  the  kames,  eskers,  and  osars  of  Maine  was 
collected  during  the  geological  surveys  of  Maine  made  by  Dr.  Jackson  and 
Professor  Hitchcock.  I  have  also  received  assistance  from  hundreds  in 
various  parts  of  the  State,  but  it  has  hardly  been  practicable  to  make  the 
proper  acknowledgments  in  detail  in  cases  where  the  information  gained 
from  others  was  subsequently  superseded  by  my  own  field  work. 

NATURE   OF  THE   ROCKS  OF  MAINE. 

A  small  area  of  sandstone  is  found  in  Perry  and  adjoining  towns  in 
the  southeastern  part  of  the  State.  With  this  exception  the  coast  region  is 
covered  by  granite,  gneiss,  mica,  and  other  coarse-grained  schists,  with 
small  areas  of  syenite,  diorite,  and  other  crj^stalline  rocks.  In  the  central 
part  of  the  State,  nearly  parallel  with  the  coast,  is  a  long  belt  of  slates  and 
other  fine-grained  schists.  Still  fartlier  north  is  a  parallel  belt  of  fossilif- 
erous  rocks — sandstones,  conglomerates,  and  limestones.  Numerous  knobs 
and  ridges  of  granite  rise  in  the  midst  of  the  other  rocks.  The  contrast 
between  these  various  rocks  is  great,  both  chemically  and  mineralogically, 
and  this  makes  it  possible  to  readily  compare  the  areas  of  different  rocks 
one  Avith  another  with  respect  to  the  composition  both  of  the  till  and  of  the 
glacial  sediments.  Most  of  these  rocks  are  tough  and  compact  in  structure 
and  contain  free  quartz;  they  are  therefore  hard  to  abrade.  Except  in  a 
few  places  the  nature  of  the  rock  is  favorable  to  the  production  of  a  great 
number  of  stones  and  bowlders.     The  great  abundance  of  gravel  in  the 


conditiojST  of  rook  in  place.  7 

glacial  sediments,  as  compared  with  the  amounts  of  sand  and  clay,  is  caused 
by  the  nature  of  the  rocks. 

COIfDITION  OF  ROCK  IIV  PLACE. 

In  Maine,  as  in  a  large  part  of  eastern  North  America,  the  solid  rock 
has  been  so  planed  and  scratched  by  the  great  ice-sheet  that  only  here  and 
there  is  there  to  be  found  any  residue  of  the  preglacially  weathered  sur- 
face. The  state  of  preservation  of  the  glacial  scratches  varies  greatly.  In 
Browuville,  Munson,  and  all  the  roofing-slate  region,  the  scratches  are 
wonderfully  well  preserved.  On  broad,  level  tops  of  hills,  where  the 
wet  surface  precluded  any  suspicion  that  the  till  had  been  eroded,  I  have 
repeatedly  found  areas  of  bare  rock  several  rods  in  diameter  ujjon  which 
miniite  scratches,  such  as  might  be  made  by  the  finest  needle  point,  are 
still  sharply  defined,  and  the  situation  of  the  rock  shows  that  they  must 
have  been  exposed  to  the  weather  ever  since  the  melting  of  the  ice.  But, 
though  the  durable  Maine  roofing  slate  has  preserved  almost  unchanged 
the  record  that  was  engraved  upon  it  by  the  drift  agencies,  it  is  far  other- 
wise with  most  of  the  other  rocks.  On  most  of  the  exposed  ledges  the 
glacial  scratches  have  either  disappeared  or  are  gradually  vanishing  because 
of  the  weathering  of  the  surface.  Over  large  areas  it  is  already  impossible 
to  ascertain  the  direction  of  the  glacial  movement  except  approximately  by 
the  forms  of  the  "roches  moutonndes"  or,  better,  by  digging  away  the 
overlying  earth,  when  the  scratches  on  the  subjacent  rock  will  usually  be 
found  perfectly  preserved.  Already  some  of  the  ledges  are  split  and 
weathered  to  a  depth  of  several  inches,  and  occasionally  to  a  depth  of  sev- 
eral feet.  All  this  indicates  the  condition  of  the  rock  before  the  coming  of 
the  ice-sheet.  During  the  unnumbered  ages  of  Mesozoic  and  Tertiary 
time  all  the  State  was  above  the  sea,  and  subaerial  weathei'ing  and  erosion 
had  done  their  long  work  upon  the  surfaces  of  upheaval.  The  hills  and 
valleys  were  in  nearly  their  present  forms,  but  the  surface  was  weathered 
and  shattered  often  to  the  depth  of  50  or  even  100  feet.  Over  most  of  the 
State  the  great  glacier  removed  the  weathered  rock  and  planed  the  surface, 
but  here  and  there  the  planing  did  not  reach  the  bottom  of  depressions  of 
weathering. 

The  weathering  of  exposed  ledges  and  bowlders  has  been  greatly  aided 
by  forest  fires  and  b)'  the  burning  of  brush  in  clearing  the  land. 


GLACIAL  GRAVELS  OF  MAINE. 


WEATHERIISTG. 


This  is  the  gross  result  of  the  action  of  the  elements  on  exposed  rocks 
and  minerals.  It  is  partly  a  chemical  process,  partly  physical  and  mechan- 
ical. The  oxygen,  watery  vapor,  carbon  dioxide,  nitric  acid,  ammonia,  and 
many  other  substances  present  in  the  air,  either  constantly  or  accidentally, 
often  combine  chemically  with  the  rocks  or  with  certain  of  their  constituent 
minerals.  Rain  and  snow  water  dissolve  many  minerals,  usually  being- 
assisted  in  this  action  by  oxygen,  carbonic  acid,  and  other  gaseous  sub- 
stances absorbed  from  the  air,  from  the  soil,  or  from  decaying  organic 
matter.  Nor  does  the  process  stop  with  the  simple  solution  of  solids  and 
liqxTids;  great  chemical  changes  often  result.  The  dissolved  substances, 
especially  the  alkaline  compounds,  become  potent  agents  to  effect  new 
chemical  decompositions.  Thus  these  substances  are  not  a  finality  but  a 
means  to  an  end. 

A  familiar  example  of  solution  and  chemical  decay,  and  a  very  com- 
mon one  in  Maine,  is  the  weathering  of  the  feldspars.  By  degrees  the  more 
soluble  alkaline  silicates  are  dissolved  and  carried  away,  leaAang  an  insolu- 
ble residue,  composed  largely  of  kaolin,  the  characteristic  ingredient  of 
clay.  In  like  manner  the  pyritiferous  slates  and  schists  are  readily  disin- 
tegrated. In  the  presence  of  rain  water  the  pyrite  (or  marcasite)  is  oxi- 
dized and  hydrated  so  as  to  become  ferrous  sulphate,  or  copperas.  In  Maine 
there  are  many  places,  known  as  "copperas  ledges,"  where  the  rock  contains 
so  large  a  proportion  of  pyrite  that  the  copperas  is  produced  in  consider- 
able quantities,  and  after  rains  in  hot  weather  there  is  a  strong  odor  of 
sulphureted  hydrogen.  At  the  Katahdin  Iron  Works  the  chemical  reac- 
tions are  still  more  complex;  the  pyritiferous  slate  is  being  rapidly  decom- 
posed, the  resulting  ferrous  sulphate  being  changed  to  ferric  hydi'ate  by 
organic  matter. 

In  addition  to  the  insidious  weakening  caused  by  chemical  decay,  we 
have  the  subsequent  process  of  fracture,  by  both  physical  and  mechanical 
forces.  The  most  common  physical  causes  of  fracture  are  unequal  expan- 
sion and  contraction  under  heat  and  cold,  and  the  expansion  of  freezing 
Avater.  Various  forces  act  mechanically  to  produce  fracture,  such  as  move- 
ments of  the  earth's  crust,  the  pressure  of  overlying  rock,  and  the  impact  of 
movincr  bodies.     The  solid  rock  mav  be  fractured  to  a  limited  extent  br  the 


WEATHERING.  9 

direct  impact  of  fluids,  such  as  air  or  water;  but  most  of  tlie  fracturing  and 
abrasion  effected  by  moving  fluids  is  due,  not  to  the  meclianical  impact  of 
the  fluid,  but  to  the  sohd  masses  which  the  fluid  hurls  or  drags  against  the 
opposing  rock. 

In  this  complex  process  of  leaching,  decomposition,  and  fracturing  is 
seen  the  explanation  of  the  formation  of  soil,  subsoil,  and  bowlders  in 
those  places  where  the  rock  of  the  earth's  crust  has  been  long  exposed  to 
the  weather.  Most  rocks  fracture  naturally  into  angular  and  rather 
2Drismatic  forms.  The  subsequent  action  of  the  weather  variously  modifies 
their  j^rimitive  shapes.  Pieces  broken  off  from  the  solid  rock  by  natural 
means  have  received  many  names,  such  as  rock  ddbris,  clifiP  debris,  frag- 
mental  debris,  angular  gravel,  float  rock,  disintegrated  rock,  weathered 
rock,  moraine  stuff,  angular  blocks,  stones  and  bowlders  of  decomposition, 
and,  when  at  the  foot  of  a  cliff,  talus.  The  words  soil,  subsoil,  sand,  and 
clay  describe  certain  states  of  weathered  rock.  Piece  after  piece  is  broke;i 
off  from  the  blocks  into  which  the  solid  rock  was  originally  shattered,  until 
the  whole  is  reduced  to  a  fine  powder,  known  as  soil ;  and  since  the  weather- 
ing usually  goes  on  faster  at  the  angles,  the  prismatic  blocks  resulting 
from  the  original  fracture  are  slowly  rounded  at  the  angles  and  become 
rounded  bowlders  of  disintegration. 

Without  the  process  of  weathering  there  would  be  no  soil  on  the  earth 
except  where  streams  and  the  sea  had  battered  the  solid  rock  to  pieces. 
Take  away  the  power  of  frost  and  heat  to  shatter  and  the  weakenino- 
effects  of  chemical  decay,  and  the  earth  as  we  know  it  would  no  longer 
exist.  When  first  upheaved  above  the  sea,  the  land  might  be  covered  by 
sand,  gravel,  and  clay,  imperfectly  fitted  to  be  a  soil.  This  would  soon  be 
eroded  away  by  the  rains  and  streams,  and  then  the  continents  would  con- 
sist of  piles  of  bare  rock  fit  perhaps  to  bear  lichens,  but  with  none  of  the 
soils,  siibsoils,  and  drift  which  now  bury  most  of  the  solid  rock  out  of 
sight  and  which  are  necessary  to  the  existence  of  the  higher  plants  and 
animals.^ 

'The  process  of  chemical  decomposition  of  the  rocks  anrt  soils  is  greatly  aided  by  the  chan"^es 
of  atmospheric  pressure.  On  a  grand  scale  these  changes  are  due  to  the  passage  of  areas  of  hi"h 
and  low  barometer;  locally  they  are  often  due  to  varying  pressure  of  the  winds.  As  the  atmospheric 
pressure  increases,  air  is  driven  down  into  the  cavities  of  the  earth,  and  when  the  pressure  is 
diminished  part  of  this  air  is  driven  out  again  by  expansion  from  within.  In  this  manner  new  sup- 
plies of  oxygen  and  carbonic  acid  are  continually  being  introduced  into  the  rocks  and  soils.  The 
process  is  also  greatly  aided  by  the  rains. 


10  GLACIAL  GRAVELS  OF  MAINE. 

TRANSPORTATION  AND  THE   DRIFT  AGENCIES. 

A  vast  amount  of  matter,  held  in  solution  by  subterranean  waters  and 
by  surface  streams,  is  constantly  being  carried  off  to  the  sea.  A  still  larger 
quantity  is  being  transported  in  the  solid  condition  by  various  other  agen- 
cies. The  term  "drift,"  as  here  employed,  denotes  solid  matter  which  for 
any  natural  cause  has  left  its  original  position  in  the  rocks,  especially  if  it 
has  traveled  a  considerable  distance. 

TRANSPORTATION  BY  LANDSLIP  AND   SOIL-CAP  MOVEMENT. 

Geologists  long  ago  declared  that  every  particle  that  has  become  loos- 
ened from  its  parent  rock  is  on  its  way  to. the  sea.  As  the  result  of  weath- 
ering, isolated  fragments  frequently  become  detached  and  fall  rapidly  and 
far  down  steep  cliffs;  thus,  for  instance,  are  stones  precipitated  upon  the 
Alpine  glaciers.  Other  fragments  are  so  slowly  undermined  that  they  fall 
only  a  little  wa,j  at  a  time,  or  at  so  slow  a  rate  that  they  slide  rather  than 
roll  down  the  slope.  In  the  canyons  of  the  Rocky  ^Mountains,  and  on  such 
of  the  slopes  of  those  mountains  as  are  covered  with  disintegrated  rock, 
many  large  bowlders  of  stratified  limestone  and  sandstone  have  slid  down 
the  mountain  sides  many,  sometimes  hundi'eds,  of  feet.  The  gravel  in 
which  they  are  partially  embedded  slowly  weathers  or  is  washed  away,  and 
the  bowlders  sink  with  so  little  disturbance  that  the  lines  of  stratification 
are  now  nearly  parallel  with  their  original  direction,  although  long  ages 
have  elapsed  since  the  bowlders  began  their  journey  toward  the  ocean. 
Every  talus  or  soil  shows  this  imperceptible  creep  of  the  separate  fi-agments, 
and  the  term  "  soil- cap  movement"  has  been  applied  to  the  process.  The 
simplest  case  is  where  fragments  move  under  the  action  of  gravity  alone. 
A  more  complex  case  arises  when  they  also  sustain  the  weight  of  other 
solid  particles,  as  often  happens  in  cases  of  rock  avalanche  and  landslide, 
which  in  mountainous  regions  are  important  di'ift  agencies.  Landslides  are 
especially  common  during  the  rainy  season,  not  only  because  of  the  lubii- 
cating  and  loosening  effect  of  water  on  a  porous  stratum,  but  also  because 
of  the  weight  of  the  absorbed  water.  As  is  well  known,  extensive  land- 
slides have  occurred  in  the  White  Mountains,  and  they  are  not  uncommon 
in  Maine. 

At  the  great  landslide  at  Goldau,  in  Switzerland,  flashes  of  light  were 
seen  to  be  emitted  from  the  moving  earth.     This  heat  and  light  must  have 


TEANSPORTATION  BY  WIND.  1  1 

been  caused  by  the  heating-  of  particles  of  crushed  rock.  The  friction  of 
the  loosened  mass  upon  the  underlying  rock,  as  well  as  the  mutual  friction 
of  the  moving  fragments,  must  produce  more  or  less  polishing  and  scratch- 
ing of  the  stones.  It  is  probable  that  it  would  be  difficult  to  distinguish 
such  stones  from  those  scratched  beneath  a  glacier. 

On  hillsides  in  Maine  the  slow,  imperceptible  sliding  characteristic  of 
the  soil-cap  movement  has  often  given  an  imperfect  stratification  to  fine, 
clayey  till.  The  till  becomes  softened  and  somewhat  i^lastic  when  saturated 
by  the  rains  or  upheaved  and  loosened  by  the  frost.  When  the  ground 
settles,  the  flat  fragments  tend  to  a  horizontal  position,  and  on  hillsides  the 
shearing  force  caused  by  the  slow  downward  movement  causes  the  laminse 
of  clay  and  plastic  materials  to  become  arranged  parallel  with  the  slopes. 
In  such  situations  the  till  often  weathers  in  layers  as  regular  as  those  of 
clay  deposited  in  water.  Part  of  this  quasi  stratification  is  doubtless  due  to 
the  pressure  and  shear  to  which  the  particles  of  the  ground  moraine  of  the 
ice-sheet  were  subjected  as  the  ice  dragged  its  vast  bulk  over  them. 

In  the  modes  of  drift  transportation  above  mentioned  gravity  acts 
directly  as  the  impelling  force.  Another  class  of  drift  agencies  comprises 
those  cases  where  the  transportation  is  effected  by  moving  liquids  or  gases, 
including  plastic  solids,  such  as  ice.  In  such  cases  gravity  acting  directly 
on  the  transported  matter  often  does  not  aid  the  movement;  instead,  the 
weight  of  the  transported  body  often  has  to  be  overcome  by  the  moving 
fluid. 

TRANSPORTATION  BY  WIND. 

Where  the  winds  are  in  general  moderate,  as  they  are  in  Maine,  and 
where  rains  or  snows  fall  at  frequent  intervals,  the  climate  is  not  well 
adapted  to  wind  transportation.  Yet  there  are  in  the  State  large  areas  of 
sand  now  drifting,  besides  multitudes  of  dunes  long  since  overgrown  with 
vegetation.     Thus  the  wind  is  seen  to  be  an  important  drift  agency. 

Most  of  the  drifting  sands  were  originally  assorted  and  deposited  by 
water.  The  process  of  drifting  generally  begins  at  some  small  depression 
in  the  sand,  such  as  the  burrow  of  an  animal.  By  degrees  the  depression 
enlarges,  and  the  sand  taken  out  of  the  hole  goes  to  make  up  a  low  ridge 
in  the  direction  in  which  it  is  blown  by  the  prevailing  winds.  It  is  the  dry 
wind  that  transports  sand,  rather  than  even  higher  winds  accompanied  by 
rain.     The  sand  grains  on  the  windward  side  of  the  ridge,  being  exposed 


12  GLACIAL  GRAVELS  OF  MAINE. 

to  the  full  force  of  the  wind,  are  blown  up  and  over  the  ridge,  soon  to  be 
followed  and  covered  by  other  grains.  When  the  wind  changes,  these  sand 
grains  maj  all  be  blown  back  again.  As  the  dry  winds  in  Maine  are  most 
frequently  from  the  west,  the  net  result  of  this  movement  back  and  forth  is 
an  uiistead}'  march  eastward.  In  places  the  dunes  have  traveled  from  1  to 
3  miles  up  and  over  hills  '200  to  300  feet  high.  Often  a  layer  of  sand  is 
left  on  the  ground  passed  over  by  the  main  dune,  and  then  the  vegetation 
characteristic  of  a  sandy  soil  appears.  Thus,  in  western  Maine  a  growth 
of  white  pines  on  high  hillsides  is  almost  always  found  on  a  dune  of  blown 
sand  or  on  ground  passed  over  by  one. 

It  is  fortunate  that  blown  sands  so  often  leave  a  trail  behind  them,  for 
the  foremost  or  principal  dune  thus  becomes  gradiially  smaller  and  its 
power  to  do  mischief  is  lost  unless  other  dunes  follow  and  overtake  it, 

Avhich  mav  happen  if  the  sand 
is  very  abundant  at  the  place 
where  it  began  to  blo■^^^  A 
large  proportion  of  the  dunes 
now  oA'ergrown  with  vegeta- 
tion have  traveled  away  from 
the  sand  plains  ^'^-here  they 
originated  into  regions  once 
covered  by  till,  clay,  or  gravel. 
In  most  cases  it  is  possible 
to  distinguish  blown  sand  from  that  deposited  in  its  present  sitrxation 
by  water,  even  when  both  are  covered  by  vegetation.  The  blown  sand 
will  be  found  at  very  irregular  elevations  and  on  western  slopes,  except 
where  it  has  been  blown  up  the  Avestern  slope  of  a  hill  and  over  its  top  and 
has  come  to  rest  on  the  eastern  slope.  Blown  sand  contains  no  very  large 
pebbles,  and  is  not  overlain  b}'  bowlders.  The  dunes  form  rounded  ridges, 
domes,  or  terraces,  and  their  forms  are  such  as  to  be  recognized  at  once  by 
the  practiced  eye.  Usually  the  country  to  the  west  of  a  dune  is  covered 
with  more  or  less  sand,  a  sign  that  the  dune  has  passed  over  it.  These 
features  are  sufficiently  different  from  those  shown  by  water-deposited  sand 
in  similar  situations  to  enable  us  usually  to  distinguish  them.  Fine  sand  is 
the  only  material  subject  to  wind  transportation  on  a  large  scale,  yet  each 


Fig.  1.— Stratification  of  wnul  blo\Mi  sand;  Lockea  Mills 


TRANSPORTATION  BY  RUNNING  WATER.  13 

year  there  is  consideraule  blowing  of  the  clay  and  the  finer  grains  of  the 
till  or  gravel,  especially  on  dry  hillsides.  It  is  this  blown  soil  which  so 
often  covers  the  snow  in  winter.  It  is  well  known  that  in  exposed  situa- 
tions fall  plowing  results  in  a  considerable  loss  of  soil.  Often  in  hillside 
pastures  little  cliffs  of  wind  erosion  can  be  seen,  worn  away  partly  by  the 
direct  impact  of  the  wind  and  partly  by  the  sand  and  small  gravelstones 
blown  against  their  sides.  In  this  way  considerable  areas  have  been 
denuded  of  their  surface  layers.  To  this  process  I  have  elsewhere  given 
the  designation  "till -burrowing."  It  is  by  far  most  active  along  the  borders 
of  drifting  sand  dunes,  partly  because  the  protecting  vegetation  has  been 
killed  by  the  sand,  and  partly  because  in  such  situations  the  surface  is 
drier  than  usual.  Thus  en  a  hilltop  about  IJ  miles  northwest  of  Wayne 
Village,  cliffs  in  the  till  were  3  feet  high  and  the  till  was  eroded  to  the 
solid  rock.  The  finer  parts  were  driven  away  and  the  rock  was  strewn 
with  the  larger  stones  of  the  till.  The  gi-avel  thus  left  is  to  be  distinguished 
from  the  other  forms  of  gravel. 

The  process  of  till-bun'owing  is  often  aided  by  sheep,  which  have  a 
habit  of  digging  into  hillsides  in  order  to  lie  in  the  shade  of  the  small  cliffs 
thiis  formed. 

TRANSPORTATION  BY  RUNNING  WATER. 

This  is  the  most  common  and  familiar  of  all  the  natural  processes  of 
drift  transportation.  The  power  of  running  water  to  transport  solid  frag- 
ments depends  on  several  elements:  (1)  According  to  Hopkins,  other  things 
being  equal,  the  power  to  transport  increases  as  the  sixth  power  of  the 
velocity.  (2)  Since  in  general  the  force  of  gravity  is  to  be  overcome,  it  is 
obvious  that  the  specific  grai^ity  of  the  drift  matter  is  to  be  taken  into  the 
account.  (3)  The  shape  of  the  fragment  to  be  transported  must  also  have 
an  influence  on  the  result,  since  this  determines  the  relative  amount  of  sur- 
face presented  to  the  force  of  the  ciuTcnt  and  often  the  fi-iction  to  be  over- 
come ;  thus  spheres  are  more  easily  transported  than  slabs  having  the  same 
weight.  (4)  The  volume  of  the  current  must  also  be  considered.  Rocks  of 
the  ordinary  kinds  have  a  specific  gravity  of  2.4  to  3.  When  submerged 
they  lose  one-third  or  more  of  their  weight,  and  they  will  be  more  easily 
transported  when  there  is  volume  of  water  sufficient  to  wholly  submerge 


14 


GLACIAL  GHAVELS  OF  MAINE. 


them.     It  has  been  esthnated^  that  the  transporting  power  of  different  rates 
of  river  flow  is  as  follows : 

Transporting  power  of  different  rates  of  river  flow. 


Rate  per 
second. 

Eate  per 
liour. 

Power  of  transportation. 

Inches. 
3 
6 
8 
12 
24 
36 

Miles. 

0.170 
.340 
.4545 
.6819 

1.  3638 

2.045 

Will  just  begin  to  work  on  fine  clay. 
Will  lift  fine  sand. 
Will  lift  sand  as  coarse  as  linseed. 
Will  sweep  along  fine  gravel. 

Will  roll  along  rounded  pebbles  1  inoli  in  diameter. 
Will  sweep  along  slipper.y  angular  stones  of  the  size  of 
an  egg. 

The  specific  gravity  of  the  gravelstones  is  not  stated,  but  presumably 
it  is  that  of  ordinary  rocks. 

The  fragments  transported  by  water  are  of  various  sizes,  and  have 
received  names  accordingly.  The  following  names  have  been  proposed  by 
Prof  T.  C.  Chamberlin: 

For  the  very  finest  particles,  mud  or  day ;  for  fragments  up  to  size  of  a 
pea,  sand;  for  fragments  varying  from  the  size  of  a  pea  up  to  about  1  inch 
in  diameter, /i?,e  gravel;  for  fragments  from  1  inch  to  3  inches  in  diameter, 
coarse  gravel;  for  rounded  stones  less  than  3  inches  in  diameter,  pehhles ;  for 
rounded  stones  from  3  to  6  inches  in  diameter,  cobbles;  for  masses  from 
6  inches  to  15  inches  in  diameter,  boivlderets;  for  masses  over  15  inches  in 
diameter,  boivlders. 

In  this  report  stones  from  the  size  of  a  pea  up  to  1  inch  in  diameter 
are  called  gravelstones,  and  the  transitions  between  mud  and  sand  are 
termed  silt. 

That  rivers  are  carrying  chift  matter  to  the  sea  is  a  matter  of  common 
observation.  The  sound  of  gravelstones  and  pebbles  rattling  against  one 
another  and  rolling  along  the  bottom  of  the  upper  courses  of  streams  can 
often  be  heard  by  one  who  puts  his  ear  near  the  bottojn  of  a  boat  or  into 
the  water.  Everyone  has  seen  streams  tear  down  portions  of  their  banks 
and  carry  them  away.     The  muddy  color  of  many  streams,  especially  in 

'David  Stevenson,  Canal  and  River  Engineering;  q^uoted  by  Geiliie,  Text-book  of  Geology, 
p.  380, 1893. 


TRANSPORTATION  BY  RUNNING  WATER.  '  15 

time  of  flood,  is  due  to  earthy  matter  suspended  in  the  water.     These  facts 
are  too  obvious  to  need  elaboration. 

SEDIMENTATION. 

For  the  present  pm-pose  it  is  not  needful  to  go  into  an  elaborate  dis- 
cussion of  that  ditiicult  subject,  the  hydimilics  of  streams  and  other  moving- 
waters.  We  have  seen  that  an  increase  in  velocity  of  currejit  causes  an 
increase  of  transporting  capacity  proportioned  to  the  sixth  powers  of  the 
velocities.  A  decrease  in  velocity  causes,  therefore,  a  proportionately 
large  decrease  in  carrying  power.  Now,  the  velocity  of  a  stream  depends, 
assuming  the  force  of  gravity  as  constant,  partly  on  degree  of  declivit}- 
and  partly  on  the  friction  to  which  it  is  subjected.  The  friction  includes 
the  viscosity  of  the  water,  the  friction  of  the  water  and  of  the  suspended 
particles  against  the  sides  and  bottom  of  the  bed,  and  the  friction  of  the 
suspended  particles  against  one  another.  In  the  case  of  currents  containing 
a  large  amount  of  solids  in  suspension,  the  friction  resulting  from  the 
presence  of  the  suspended  matter  becomes  so  great,  as  compared  with  the 
other  sources  of  friction,  that  the  velocity  is  determined  chiefly  by  the  load 
of  sediment  the  stream  has  to  carry.  Any  enlargement  of  the  channel  of 
an  ordinary  stream,  unless  accompanied  by  a  corresponding  increase  of 
water  supply,  causes  a  slowing  of  the  current.  Conversely,  a  narrowing 
of  the  channel  acts  like  a  partial  dam;  it  increases  the  slope  of  the  surface 
and  is  accompanied  by  a  more  rapid  flow.  Any  slowing  of  the  current 
will  cause  matter  which  coifld  just  be  transported  at  the  former  velocity  to 
be  thrown  down.  Such  matter  is  called  sediment,  and  the  same  term  is 
often  applied  to  particles  of  solid  matter  while  they  are  yet  held  in  suspen- 
sion. Aqueous  sediment  naturally  settles  in  successive  layers,  and  such 
drift  is  said  to  be  stratified.  When  the  current  is  of  uniform  velocity,  the 
particles  deposited  are  of  uniform  size.  Upon  this  depends  the  sorting  or 
classifying  power  of  water. 

One  of  the  most  common  applications  of  these  principles  is  seen  when 
a  sediment-laden  stream  flows  into  a  large  body  of  rather  still  Avater,  like 
the  sea  or  a  lake.  The  currents  are  checked  gradually,  and  there  is  a  hori- 
zontal assortment  of  sediment,  the  coarsest  matter  being  deposited  near  the 
mouth  of  the  stream  and  the  sediment  becoming  progressively  finer  as  the 


16  ■  GLACIAL  GRAVELS  OP  MAINE. 

current  gradually  loses  its  motion.  Such  delta  deposits  are  exceedingly 
common  in  Maine. 

Aqueous  sediments  are  termed  torrential  wlien  deposited  by  very  rapid 
streams,  fluviatile  when  deposited  by  ordinary  rivers,  lacustrine  or  lacustral 
when  deposited  in  lakes,  marine  when  in  the  sea,  and  estuarine  when  in  that 
portion  of  a  river  subject  to  the  ebb  and  flow  of  the  tides.  While  in  one 
sense  a  portion  of  the  sea,  the  estuary  is  inclosed  like  a  river,  and  therefore 
its  deposits  differ  from  those  of  the  open  sea.  The  water  is  more  or  less 
brackish,  and  only  the  remains  of  animals  naturally  frequenting  such  places 
are  found  in  estuarine  sediments. 

The  sediment  deposited  by  rains  and  streams  on  the  land  is  termed 
alluvium,  and  when  in  the  valleys  of  ordinary  streams  it  is  often  named 
valley  drift.  Observations  in  all  parts  of  New  England  show  that  a  very 
large  amount  of  alluvium  was  deposited  in  the  larger  valleys  at  or  near  the 
close  of  the  Glacial  period.  So  characteristic  is  this  alluvium  that  the 
period  has  sometimes  been  termed  the  Valley  Drift  period. 

The  principles  enunciated  above  enable  us  to  estimate  approximately 
the  velocities  of  the  rivers  at  the  time  the  valley  drift  wac  deposited.  The 
size  of  the  fragments  contained  in  the  valley  drift  is  such  that  the  velocity 
necessary  to  transport  them  is  generally  less  than  4  or  5  miles  per  hour, 
but  among  the  hills  it  may  have  reached  8  or  10  miles.  This  refers  to  the 
velocity  near  the  bottom  of  the  streams.  The  slope  required  to  produce 
these  velocities  varies  according  to  the  breadth  and  depth  of  the  stream,  etc. 

The  viscosity  of  water  is  so  small  that  only  very  swift  currents  can 
transport  large  stones  and  bowlders  up  and  over  a  steep  obstacle.  The 
water  at  the  bottom  is  embayed  or  dammed  by  the  obstacle,  so  that  the 
rest  of  the  stream  flows  over  and  around  the  embayed  water  as  well  as  the 
obstacle.  Hence,  the  mutual  adhesion  of  the  pebbles  of  a  gravel  bank  is 
often  sufficient  to  protect  the  bank  from  erosion  when  the  velocity  of  the 
current  is  far  greater  than  would  otherwise  suffice  to  transport  the  pebbles. 
The  pebbles  become  wedged  together  like  paving  stones,  so  that  they  can 
not  be  moved  without  friction,  and  they  resist  erosion  by  swift  currents  as 
the  gravels  of  the  seabeach  resist  the  surf. 

A  practical  application  of  these  principles  involves  the  vexed  question: 
How  can  we  account  for  the  presence  of  stones  several  inches  in  diameter 
in  the  midst  of  fine  sand  and  clay  !     It  has  been  usual  to  refer  the  cobbles 


SEDIMENTATION.  17 

and  bowlderets  found  in  the  valley  drift  to  ice  floes.  No  doubt  ice  floes 
often  deposited  such  stones,  as  well  as  large  bowlders,  but  I  have  lately 
made  some  observations  in  Colorado  which  show  that  large  stones,  and  even 
bowlders,  may  be  deposited  by  water  upon  and  within  sand.  I  have 
examined  the  track  of  several  so-called  cloudbursts  soon  after  they  occurred. 
Near  the  centers  of  these  violent  thunderstorms  a  fall  of  6  or  8  inches  of 
rain  and  hail  is  not  unusual.  This  great  precipitation  takes  place  within  a 
few  hours,  sometimes  within  a  few  minutes.  The  rain  water  soon  collects 
on  the  lower  slopes,  fills  the  beds  of  the  streams,  and  then  covers  their 
flood  plains  to  a  depth  of  several  feet,  sometimes  overwhelming  a  broad 
prairie.  As  the  waters  flow  down  the  hillsides  the  hail  is  rolled  along  in 
front  as  a  sort  of  moving  dam  several  feet  liigh.  Here  and  there  the  waters 
break  through  this  dam  and  shoot  with  great  velocity  down  the  slopes  of 
the  prairie,  soon  to  be  stopped  again  by  the  hail.  In  this  way  the  waters 
are  soon  concentrated  and  confined  within  channels  varying  from  10  feet  to 
several  hundi-ed  feet  in  breadth,  bordered  by  walls  or  dams  of  hail  from  1 
to  4  feet  high. 

During  one  of  these  floods  in  El  Paso  County  the  flow  was  so  rapid  as 
to  transport  slabs  of  sandstone  4  feet  square  and  2  feet  thick.  These 
bowlders  were  iron-cemented  and  heavier  than  ordinary  sandstone.  The 
velocity  of  the  current  must  have  been  10  miles  oi-  more  j)er  hour.  ■  In 
narrow  ravines  of  erosion  (washes  or  arroyos)  the  erosion  was  very  great. 
Blocks  of  clay  were  undermined  and  rolled  along  in  the  boiling  torrent 
until  they  were  nearly  round.  A  stream  200  to  300  feet  wide,  and  about 
20  feet  in  depth  at  the  deepest  place,  issued  from  the  mouth  of  a  narrow 
valley  at  Templetons  Gap,  near  Colorado  Springs.  It  became  somewhat 
wider  as  it  entered  the  broad  open  plain,  yet  for  one-third  of  a  mile  it  was 
swift  enough  to  transport  the  bowlders  above  mentioned.  Previous  to  the 
flood  the  plain  at  this  point  was  composed  of  sand  loosely  grassed  over. 
The  bowlders  were  dropped  upon  the  sand  plain,  which  was  but  little 
eroded  by  the  swift  currents.  Then  as  the  flow  slackened,  sand  was  depos- 
ited upon  and  around  the  bowlders  to  the  depth  of  from  1  to  3  feet.  The 
geologist  of  the  future  will  find  the  bowlders  surrounded  on  all  sides  by 
stratified  sand.  Before  I  saw  and  studied  these  cases  it  would  have  seemed 
to  me  impossible  that  water  could  have  deposited  fine  sand  and  large 
bowlders  in  juxtaposition  in  this  way.     Two  or  tln-ee  miles  farther  down  on 

MON  XXXIV 2 


18  GLACIAL  GEAVELS  OF  MAIXE. 

the  plain,  the  flood  crossed  recently  plowed  fields.  The  surface  was  eroded 
somewhat  and  was  left  with  numerous  swells  and  hollows,  up  to  a  foot  in 
depth,  3"et  this  small  erosion  was  produced  Idj  currents  sAvift  enough  to  roll 
along'  mud  lumps  a  foot  in  diameter.  About  5  miles  below  where  the  flood 
issued  from  the  narrow  valley,  it  became  concentrated  between  banks  of 
hail  and  swept  awa}'  a  house  situated  on  an  open  plain  in  the  city  of 
Colorado  Springs. 

These  and  numerous  similar  observations  in  Colorado,  both  in  the 
recent  water  drift  and  in  that  of  Tertiary  age,  show  bowldei's  of  consid- 
erable size  surrounded  by  fine  sand  and  gravel  and  occasionally  embedded 
in  clay.  It  thus  appears  that  swift  currents  can  flow  over  a  stratum  of  fine 
sediment  having  an  even  or  level  surface  without  eroding-  it  much,  due 
largely  to  the  fact  that  the  lower  part  of  the  water  is  nearly  stopped  by 
friction.  The  stream  can  not,  so  to  speak,  get  at  the  .sediment  while  it 
remains  coherent.  But  when  a  stream  impinging  ag-ainst  a  vertical  bank 
undermines  a  portion  of  it,  the  alluvium  usually  loses  its  coherence  the 
moment  it  is  precipitated  into  the  water.  The  particles  now  being  isolated 
are  no  longer  able  to  protect  one  another  by  mutual  cohesion  and  friction. 

These  observations  have  a  bearing  not  only  on  the  occurrence  of  large 
stones  and  bowlders  in  the  valley  di'ift,  but  also  on  the  bowlder  beds  found 
in  ancient  rocks.  I  consider  it  certain  that  large  stones  and  even  bowlders 
may  be  deposited  by  running  water  in  the  midst  of  sediments  as  fine  as 
sand,  and  even  in  clay.  What  is  required  is  a  rapid  current  moving  over 
an  even  surface  and  acting  for  a  rather  short  time.  The  sudden  storms  of 
the  Rocky  Mountains  furnish  the  required  rush  of  water,  and  it  is  quite 
possible  that  the  spring  floods  of  the  Valley  Drift  period  also  aftbrded  the 
necessary  conditions. 

Large  stones  found  in  the  sedimentary  marine  clays  must  ha-\-e  been 
cb-opped  from  above  by  ice  or  other  floating  body. 

TRANSPORTATION  AND  EROSION  BY  SPRINGS  AND  SUBTERRANEAN  STREAMS. 

This  important  means  of  erosion  and  transportation  has  not  hitherto 
received  from  students  of  the  drift  the  consideration  it  deserves. 

The  action  of  subterranean  water  is  not  very  rapid,  but  it  is  persistent. 
The  rain  seeping  down  through  the  earth  dissolves  some  of  its  ingredients. 
At  depths  below  the  reach  of  frost  this  process  slowly  enlarges  the  spaces 


TEAXSPOETATION  AND  EROSION.  19 

between  the  particles.  Under  favorable  circumstances  the  interspaces  by 
degrees  become  so  large  that  minute  sand  or  clay  particles  are  carried 
along  by  the  water,  and  thus  mechanical  attrition  helps  to  enlarge  still 
inore  the  passages  between  the  grains  of  earth.  In  numerous  wells  in  the 
glacial  till  the  water  has  been  reported  as  being  found  in  "gravel."  I  have 
examined  several  such  wells  and  found  that  subterranean  waters  had 
percolated  through  the  till  until  they  had  carried  off  the  finer  particles, 
leaving  the  larger  stones  somewhat  rounded  by  the  flow.  I  infer  that  Avhen 
the  till  was  first  formed  the  water  percolated  through  all  parts  of  the  mass 
at  a  nearly  uniform  rate.  By  degrees  the  seeping  became  more  rapid  along 
certain  lines  or  layers,  where  there  was  the  largest  water  supply  or  the 
most  matter  readily  removable.  These  layers  soon  became  more  porous 
than  tlie  rest  of  the  till  and  formed  a  system  of  subterranean  streams  or 
"veins."  In  my  early  studies  of  the  till  I  was  often  puzzled  at  these 
apparently  water-washed  beds  of  gravel  in  what  would  otherwise  be 
amorphous  till.  This  phenomenon  occurs  in  the  granitic  and  clay-slate 
regions  as  well  as  elsewhere.  In  such  regions  the  surface  waters  do  not 
sink  down  into  the  till  in  large  streams,  like  the  sinks  of  a  limestone  region, 
and  the  till  is  in  most  cases,  perhaps  in  all,  compact  enough  to  thoroughly 
filter  the  water  before  it  has  penetrated  many  feet.  The  presence  of  muddy 
water  in  a  deep  well  that  is  protected  from  surface  wash  around  its  mouth 
indicates  subterranean  erosion  rather  than  access  of  muddy  sm-face  waters. 
Such  cases  have  happened  to  my  knowledge.  However,  this  erosion  is 
rarely  so  rapid  as  to  muddy  the  water  perceptibly.  Ob\'iously  the  longer 
the  process  continues  the  more  porous  the  subterranean  channels  become, 
and  the  escape  of  the  waters  will  be  more  rapid  with  correspondingly 
rapid  erosion. 

When  water  is  flowing  through  a  porous  stratum,  especially  of  sand, 
with  such  velocit)'  as  to  overcome  the  mutual  adhesion  of  the  grains  and  to 
carry  them  along  with  it,  we  have  what  is  known  as  quicksand.  In  like 
manner,  gravel  will  flow  like  a  liquid  if  water  flows  rapidly  through  it. 
This  is  the  cause  of  the  very  great  amount  of  erosion  effected  by  what  are 
known  as  "boiling  springs."  I  have  elsewhere  recorded  instances  of  large 
ai-eas — square  miles— of  porous  gravel  eroded  and  removed  b}'  boihng 
springs  assisted  by  surface  waters.  When  a  stream  impinges  against  a 
gravel  bank,  the  stones  b}'-  their  mutual  adhesion  protect  one  another  from 


20  GLACIAL  GRAVELS  OF  MAINE. 

the  force  of  the  ciirrent.  But  when  water  passes  from  beneath  upward 
tlirough  the  gravel,  the  surface  stones  and  grains  are  one  by  one  hfted  from 
the  others  and  the  water  bears  them  away  as  if  they  were  a  part  of  itself. 
Thus  the  principal  eroding  and  transporting  work  of  subterranean  waters  is 
done  as  they  approach  the  surface  as  springs.  There  is  an  increased 
velocity  as  the  water  nears  the  place  of  its  release,  and  all  loose  matter 
approaches  the  condition  of  quicksand.  Clay  and  till  are  so  compact  that 
they  have  suffered  comparatively  little  in  this  way,  but  the  quantity  of 
porous  sand  and  gravel  thus  removed  is  surprising. 

TRANSPORTATION    BY    GLACIERS. 

For  the  purpose  of  this  report  it  is  not  needful  to  discuss  questions 
relating  to  the  structure  or  behavior  of  glaciers,  except  so  far  as  pertains  to 
the  geological  work  performed  by  them.  We  assume  that  snow  which  lasts 
from  year  to  year  finally  becomes  consolidated  into  ice.  Above  the  line  of 
perpetual  snow  the  ice  and  semiconsolidated  snow  are  known  as  the  ndvd, 
or  firn ;  below  that  line,  as  the  glacier  proper.  Under  favorable  conditions 
the  ice  slowly  flows,  at  a  rate  varying  according  to  the  temperature,  the 
pressure  from  behind  or  the  tension  from  before,  the  friction,  the  declivity 
of  the  surface  over  which  it  moves,  etc.  Whether  this  is  a  true  molecular 
flow  or  only  the  apparent  flow  of  a  plastic  body — of  masses  larger  than 
molecules — it  is  not  necessary  now  to  determine.  Under  sufficient  tension, 
or  stretching  force,  the  ice  breaks,  producing  cracks  called  crevasses,  which 
are  known  as  longitudinal  or  transverse  according  to  their  direction  with 
respect  to  the  length  of  the  glacier,  or  marginal  when  at  the  sides.  When 
fractured  surfaces  of  moist  ice  are  brought  together,  they  at  once  cohere, 
and  surfaces  of  dry  ice  brought  together  under  sufficient  pressure  also 
cohere.  Thus,  no  matter  how  often  the  glacier  is  rent  and  torn,  it  has  the 
power  to  heal  its  own  wounds  and  to  flow  on,  practically  as  solid  as  before. 

Glacial  movement  conforms  to  the  general  laws  of  flow  of  fluids.  The 
flow  is  from  where  there  is  greater  pressure  to  where  there  is  less,  and  it  is 
retarded  by  friction  at  the  bottom  and  sides  of  the  glacier.  This  friction  is 
but  another  name  for  the  force  which  the  glacier  exerts  in  its  efPorts  to  push 
along  the  rock  and  other  substances  in  contact  with  it. 

When  weathered  rocks  project  above  the  glacier,  more  or  less  cliff 
d(ibris  tumbles  down  upon  the  ice.     This  debris  is  known  as  moraine  stuff", 


TEANSPOETATION  BY  FLOATING  ICE.  21 

and  a  mass  of  it  is  caned  a  moraine.  Moraines  are  lateral,  medial,  basal, 
or  terminal,  according  to  tlieir  situation  with  respect  to  the  glacier.  Moraine 
stuff  falling  into  crevasses  is  carried  forward  by  the  ice,  and  in  this  trans- 
portation the  stones  often  scratch  one  another  or  the  solid  rock.  Moraine 
stuff  beneath  the  ice  is  known  as  a  moraine  profonde,  or  ground  moraine. 
In  ordinary  valley  glaciers,  such  as  those  of  the  Alps,  the  ground  moraine 
forms  but  a  small  proportion  of  the  moraine  stuff.  But  where  the  whole 
countr}^  is  covered  by  ice,  and  no  cliffs  project  above  it,  the  whole  of  the 
moraine  stuff'  is  beneath  the  ice  or  distributed  through  it.  Most  of 
the  melting  of  the  ice  takes  place  at  the  surface.  The  melting  waters  then 
run  along  on  the  surface  until  they  reach  a  deep  crevasse,  down  which  they 
pour,  and  make  their  escape  by  tunnels  beneath  the  glacier.  In  this  way 
each  glacier  is  drained  by  one  or  more  subglacial  streams.  The  waters  of 
these  streams  are  usually  muddy  and  heavily  loaded  with  the  finer  detritus 
resulting  from  the  grinding  of  moraine  fragments  against  one  another  and 
against  the  underl}-ing  rock.  In  its  impetuous  course  the  subglacial  stream 
erodes  its  bed,  sand-carves  the  rock,  and  forms  potholes,  like  other  swift 
streams.  During  the  winter,  when  the  supply  of  water  is  diminishing,  the 
lower  portions  of  the  tunnels  of  the  subglacial  streams  become  clogged 
with  rounded  sand  and  gravel.  When  the  ice  is  thick,  it  is  able  to  jnish 
this  gravel  onward  and  finally  deposit  it  as  a  part  of  the  terminal  moraine, 
but  a  thin  glacier  will  flow  over  its  subglacial  sediments  without  disturbing- 
even  the  lines  of  stratification. 

The  general  nature  of  the  work  done  by  glaciers,  as  stated  in  this  brief 
outline,  has  been  established  by  the  observations  of  so  man}"  persons  that 
it  is  here  assumed  without  attempt  at  proof  Some  controverted  points  will 
be  discussed  hereafter. 

TRANSPORTATION    BY    FLOATING    ICE. 

Icebergs. — These  are  masses  broken  off'  from  the  fiont  of  a  glacier.  They 
carry  more  or  less  moraine  stuff',  which  sinks  to  the  bottom  of  the  sea  or 
lake  when  the  ice  melts. 

Ice  floes. — These  are  composed  of  the  ice  formed  along  the  shores  of  the 
sea  or  of  a  lake  They  often  contain  numbers  of  the  stones  and  bowlders 
of  the  beach,  frozen  fast  in  them.  Other  things  being  equal,  ice  floes  are 
thickest  where  the  tide  rises  and  falls.     In  the  spring  they  first  melt  nearest 


22  GLACIAL  GRAVELS  OF  MAINE. 

the  readily  warmed  shore,  and  thus  become  detached.  They  then  drift 
hither  and  thither  under  the  action  of  winds  or  tides,  and  finally  drop  their 
burden  of  drift  upon  the  floor  of  the  sea  or  lake,  or  upon  the  shore  where 
they  may  have  been  stranded. 

River  ice. — This  differs  from  the  floe  of  shore  ice  only  in  situation.  The 
ice  of  rivers  freezes  fast  to  stones  and  bowlders,  either  on  the  shores  or  in 
shallow  channels.  When  the  ice  breaks  up  in  the  spring,  these  stones  and 
bowlders  are  often  transported  long  distances.  Frequently  as  the  ice  goes 
out  it  forms  jams  or  gorges  in  its  channel.  When  the  dam  at  last  yields  to 
the  pressure  of  the  water  behind  it,  the  ice  often  pushes  along  with  it  large 
quantities  of  bowlders  and  other  drift.  The  moving  ice  dam  acts  as  a  sort 
of  glacier,  the  units  of  ice  motion  being  the  blocks  of  ice,  and  not  indeter- 
minate masses,  as  in  the  glacier.  Similar  dams  must  frequently  form  in 
the  channels  of  superficial  streams  on  the  ice,  as  well  as  in  those  of  the 
subglacial  streams. 

SHAPES   OF   DPaFT   FRAGMENTS. 

Crystalline  forms,  or  those  due  to  crystalline  cleavage. In  Maiue,  UOt   UUfreqUently,  CryS- 

tals  of  garnet,  quartz,  and  other  hard  minerals  can  be  found  in  sand  and 
other  forms  of  drift.  Easily  cleavable  minerals,  such  as  feldspar,  are 
usually  found  in  their  cleavage  forms,  more  or  less  modified  by  attrition. 

Fracture  forms. — Thcse  are  tlic  augular,  prismatic,  or  more  or  less  irregular 
forms  into  which  rocks  and  minerals  fracture  under  the  influence  of  heat 
and  cold,  joints,  etc.  The  forms  vary  according  to  the  composition  and 
structure  of  the  rocks,  each  kind  of  rock  having  a  prevailing  form  peculiar 
to  itself  These  forms  are  so  characteristic  that  one  can  often  know  the 
nature  of  a  bowlder  from  its  shape  alone. 

Weather-rounded  forms. — When  Tocks  are  of  ratlicr  uniform  composition  and 
structure,  their  fracture  forms  naturally  weather  faster  at  the  exposed  angles, 
and  thus  tend  toward  the  spherical  form.  For  instance,  the  surface  of  a 
weathered  granite  bowlder  is  somewhat  rough,  being  composed  of  a  great 
number  of  small  crystalline,  fracture,  and  cleavage  surfaces,  but  its  general 
shape  is  rounded.  The  most  of  the  granitic  and  syenitic  bowlders  owe  their 
rounded  shapes,  not  to  the  attrition  of  the  glacier,  but  to  weathering.  They 
are  no  rounder  than  similar  bowlders  under  the  tropics  in  Egypt.  A  good 
example  of  the  progressive  changes  from  angular  blocks  of  fracture  to 


SHAPES  OF  DRIFT  FRAGMENTS.  23 

rounded  bowlders  of  weathering  can  be  seen  on  the  southern  brow  of 
Russell  Mountain,  in  the  town  of  Blauchard,  Maine. 

Weather-carved  forms. — Wlieu  the  compositiou  Or  sti'ucture  of  a  rock  is  not 
uniform,  the  weathering  may  proceed  in  some  directions  more  rapidly  than 
in  others.  The  longer  such  a  rock  is  exposed  to  the  weather  the  more 
irregular  its  shape  becomes.  In  this  way  curious  depressions  have  fre- 
quently been  formed  on  granite  or  other  crystalline  and  nonfossiliferous 
rocks,  which  have  often  been  supposed  to  be  the  tracks  of  men  or  the  lower 
animals  or  of  infernal  beings.  On  the  islands  of  Monhegan  and  Menana, 
off  the  coast  of  Maine,  are  certain  markings  on  the  rocks  which  have  been 
described  by  archeologists  as  inscriptions.  The  rather  shallow  depressions 
forming  the  so-called  letters  are  formed  along  three  systems  of  joints  of  the 
rock.  Not  a  "letter"  could  I  find  that  had  not  a  crack  (often  minute)  in 
the  rock  at  the  bottom  of  the  depi'ession.  In  numerous  instances  fractures 
of  the  rock  near  by  have  depressions  along  them,  but  no  cross  fractures  or 
depressions  to  form  letters.  It  is  evident  that  weathering  would  proceed 
most  rapidly  on  each  side  of  such  cracks,  and  thus  in  time  a  depression 
would  be  made  along  the  line  of  fracture.  The  geological  evidence  is  thus 
conclusive  that  the  markings  may  he  simply  freaks  of  weathering  along  the 
fracture  lines  of  the  rocks,  and  that  no  human  agency  is  needed  to  account 
for  them.  Yet  if  these  markings  prove  to  be  capable  of  decipherment,  we 
shall  have  to  assume  the  existence  of  a  race  of  men  acute  enough  to  take 
advantage  of  natural  fractures  and  to  form  letters  along  them. 

In  the  western  part  of  Oxford  County  are  many  bowlders  of  a  black 
eruptive  rock  which  often  have  very  uncouth  and  unusual  shapes.  This  is 
due  to  unequal  weathering  of  the  stones.  When  gathered  and  placed  in 
trains  along  the  walks  near  the  houses,  they  remind  one  of  the  purposed 
hideousness  of  heathen  idols. 

Water-rolled  forms. — Water  has  but  Httlc  ability  to  grind  and  polish  rock  by 
its  own  impact  and  friction.  It  derives  its  great  power  immediately  from 
the  solid  matter  which  it  is  able  to  move.  In  rolling  drift  fragments  it 
acts  in  two  ways — by  concussion  and  by  attrition.  In  the  first  case  the 
fragments  are  hurled  against  one  another  or  against  the  solid  rock,  and 
since  the  angles  are  most  exposed  to  the  blows  and  are  also  most  easily 
broken,  the  stones  are  reduced  to  the  well-known  rounded  form  of  beach 
pebbles.     In  the  second  case  the  fragments  are  pushed  past  one  another, 


24  GLACIAL  GEAVELS  OF  MAIXE. 

grinding  themselves  and  wearing  away  the  nnderlying  rock.  Concussion 
and  attrition  nsnally  accompany  each  other,  and  it  is  sometimes  difficnk  to 
distinguish  between  them.  Concussion  alone  would  leave  the  surfaces  with 
small  granular  projections.  It  is  the  office  of  attrition  to  rub  these  off.  The 
attrition  scratches  of  water-transported  fragments  are  necessarily  short, 
since  friction  against  the  sides  of  the  stones  causes  them  to  rotate,  tluis 
giving  them  a  tumbling  motion,  with  consequent  concussion.  The  distance 
traveled  by  water-rolled  pebbles  in  becoming  rounded  must  depend  on 
many  circumstances,  including  the  velocity  of  the  current,  the  abundance 
of  the  drift,  the  condition  of  the  bed  of  the  stream  (whether  a  uniform 
declivity  or  a  series  of  waterfalls  and  rapids),  and  the  size,  specific  gravity, 
hardness,  brittleness,  etc.,  of  the  fragments. 

Forms  carved  by  water-borne  sand. — Frictlou  Is  rliythmical,  aud  whcucver  the 
solid  rock  or  fragments,  which  for  any  cause  are  stationary  for  a  consider- 
able time,  are  swept  by  rapid  currents  bearing  sand  and  gravel,  they  are 
carved  into  conchoidal  depressions  or  furrows  separated  by  rather  angular 
ridges  usually  tranverse  to  the  motion.  Sand  carving  shows  what  sort  of 
work  is  constantly  being  done  by  the  finer  detritus — if  not  too  fine — trans- 
ported by  a  stream.  Stones  which  from  time  to  time  are  moved  into  new 
positions  owe  their  shapes  to  concussion  and  attrition  of  lai'ge  stones  as  well 
as  to  sand  carving,  and  do  not  show  the  peculiar  depressions  due  to  the 
rhythmical  movement  of  the  water  over  a  stationary  surface.  Instances  of 
sand  carving  can  be  seen  at  most  of  the  rapids  and  waterfalls  of  Maine 
where  the  rock  is  hard  and  resists  weathering  sufficiently  well.  Quartz 
veins  in  granite  afford  the  finest  examples  of  this  process,  as,  for  instance, 
those  at  Rumford  Falls.  Sometimes  the  peculiar  markings  of  sand  carving 
are  very  distinct  on  small  stones  which  have  become  wedged  into  a  cavity 
of  the  solid  rock.  I  found  some  such  near  the  head  of  Rumford  Falls 
which  might  have  remained  fixed  in  position  for  several  years.  The  upper 
extremity  was  faceted  to  a  plane  surface,  except  that  it  showed  the  con- 
choidal grooves  characteristic  of  sand  carving  as  distinctly  as  any  of  the 
rock  in  situ.  The  pebbles  of  sea  and  lake  beaches  are  perhaps  rounded 
more  by  concussion  than  b)^  attrition.  According  to  Sorby  and  Daubre'e, 
very  fine  sand  grains  remain  angular  after  motion  in  water. 

Forms  carved  by  wind-blown  sand. — Saud  aud  fiuc  gravel,  wlieii  impelled  by  the 
wind  against  bowlders  and  other  stationary  objects,  rapidly  wear  them 


■  SHAPES  OF  DRIFT  FRAGMENTS.  25 

away.  In  this  manner  the  upper  surfaces  of  stones  barely  projecting  above 
the  ground  are  faceted  to  nearly  a  plane,  but  with  more  or  less  of  the  trem- 
ulous grooving  due  to  the  rhythmical  friction  of  the  wind.  The  grooves 
are  usually  a  little  deeper,  as  compared  with  their  breadth,  when  made  by 
the  wind  than  when  made  by  moving  water.  Sand-carved  bowlders  are 
very  common  in  western  Maine  near  the  White  Mountains,  especially  on 
hillsides  facing  the  north  and  west.  Thus  certain  bowlders  of  peculiar 
shape  were  discovered  by  Dr.  N.  T.  True  at  Bethel  Village,  and  were 
described  in  1861  by  Prof.  C.  H.  Hitchcock,  in  a  general  report  upon  the 
geology  of  Maine.^  As  I  have  elsewhere  stated,^  these  bowlders  owe  their 
unusual  shapes  to  sand  carving  under  the  action  of  the  wind.  Occasionall)^ 
I  have  noted  sand-carved  bowlders  in  eastern  Maine,  and  many  ledges  near 
the  seashore  are  carved  witli  sand  by  both  the  wind  and  the  surf  The 
j)rocess  must  be  common  elsewhere,  but  it  can  be  recognized  only  where  it 
is  more  rapid  than  the  process  of  weathering.  The  stride  made  by  wind- 
blown sand  and  gravel  are  usually  invisible,  and  when  best  developed  are 
very  short,  owing  to  the  ready  rotation  of  the  flying  grains  and  stones 
when  they  strike  obliquely  against  a  stone  or  bowlder. 

Forms  scratched,  planed,  and  polished  by  ice  and  rocks. H)     By    £flacierS.         StOUeS    Sub- 

jected  to  attrition  b}-  glacier  action  are  said  to  be  glaciated.  Many  of  the 
glaciated  stones  show  distinct  scratches,  furrows,  or  striae.  But  where,  as  is 
often  the  case  in  the  till,  the  stones  were  rubbed  by  the  finer  detritus 
beneath  or  within  the  ice,  the  surfaces  received  a  very  fine  polish  and  show 
no  distinct  scratches  to  the  unassisted  eye.  Glaciated  stones  are  often 
faceted  and  are  almost  always  unequall}^  glaciated,  some  place  still  retain- 
ing its  original  surface  or  fracture.  (2)  By  icebergs.  When  icebergs  grind 
off  a  coast,  the  underlying  rock  must  be  corraded  and  scratched  by  any 
stones  that  happen  to  be  in  the  lowest  part  of  the  ice  and  by  any  sand  or 
other  detritus  or  rock  fragments  resting  on  the  floor  of  the  sea.  The  frag- 
ments would  also  be  scratched  and  ground.  (3)  By  shore  ice,  ice  floes,  and 
river  ice.  As  shore  ice  rises  and  falls  with  the  tide  or  is  urged  toward  the 
land  by  winds  and  the  pressure  of  ice  floes,  there  must  be  considerable 
attrition  of  the  beach  pebbles.  Floating  river  ice  must  also  produce  a  sim- 
ilar effect,  especially  when  ice  gorges  have  been  formed.     (4)  By  landslips. 

■  Sixth  Annual  Eeport  of  the  Secretary  of  the  Maine  Board  of  Agriculture,  pp.  266-267,  Augusta,  1861. 
^Am.  Jour.  Sci.,  3d  series,  vol.  31,  pp.  133-138,  Feb.,  1886. 


26  GLACIAL  GRAVELS  OP  MAINE.     • 

The  immense  amount  of  earth  mvolved  in  the  Willey  Slide  in  the 
Crawford  Notch,  and  in  several  other  large  slides  in  the  White  Mountains, 
which  were  from  one-half  mile  to  near  3  miles  long,  makes  it  certain  that 
there  must  have  been  a  vast  amount  of  friction  of  the  moving  fragments 
against  one  another  and  against  the  underlying  rock.  The  motion  of  the 
landslip  is  very  much  more  rapid  than  that  of  any  glacier,  and  this  would  be 
favorable  to  the  scratching  and  faceting  of  stones.  No  one  appears  to  have 
reported  finding  such  stones  under  circumstances  showing  conclusively 
that  they  were  formed  during  the  slip. 


CHAPTER   III. 

PRELIMINARY     DESCRIPTION     OF     THE     SUPERFICIAL 
DEPOSITS    OF    MAINE. 

A  brief  general  description  of  the  drift  of  Maine  will  be  given  in 
language  which  for  the  greater  part  is  consistent  with  any  theory  as  to  the 
origin  of  the  drift. 

Erosion  is  the  general  name  given  to  the  process  whereby  a  portion 
of  the  parent  rock  is  removed  from  its  place  by  any  geological  agency.  It 
is  a  complex  process,  consisting  of  the  preparatory  work  of  detaching 
fragments  from  their  original  position  by  solution,  chemical  decay,  weath- 
ering, water-logging  of  porous  beds,  abrasion,  concussion,  and  all  other 
forms  of  fracture,  and  of  their  subsequent  removal  by  some  drift  agency. 
The  w.ord  is  sometimes  used  for  the  preparatory  work  only,  exclusive  of 
the  subsequent  removal. 

PBEGLACIAL  DEPOSITS. 

So  far  as  yet  determined,  all  the  rocks  of  Maine  are  Paleozoic  or  still 
more  ancient.  The  fact  that  no  marine  beds  of  Mesozoic  or  Tertiary  age 
are  found  proves  that  the  area  within  the  State  has  been  above  the  sea 
since  Paleozoic  time — unless,  indeed,  deposits  of  later  age  have  been  eroded 
or  remain  to  be  discovered.  At  Brandon,  Vermont,  are  sediments  deposited 
in  a  Tertiary  lake  of  fresh  water.  Although  they  were  not  so  firmly  cemented 
and  consolidated  as  the  ancient  rocks,  the  great  glacier  was  not  able  wholly 
to  erode  them.  Similar  beds  might  have  been  laid  down  in  Maine,  and,  if 
extensive,  might  have  escaped  erosion  by  the  ice-sheet.  I  have,  therefore, 
carefully  examined  the  till,  especially  in  the  vicinity  of.  the  deeper  lake 
basins,  but  thus  far  have  found  no  fragments  of  such  Tertiary  beds.  It 
has  long  been  known  that  marine  beds  of  Tertiary  age  are  found  on  the 
coast  of  southeastern  Massachusetts,  and  fragments  have  been  dredged  off 


28  GLACIAL  GEAYELS  OF  MAINE. 

the  coast  a  short  distance  north  of  Boston.  Such  beds  must  have  been 
formed  on  the  coast  of  Mame  as  it  existed  at  that  pt-iod.  Where  are  they! 
That  they  are  now  beneath  the  sea  is  indicated  by  the  contour  of  the 
coast.  Prof.  J.  D.  Dana  has  rightly  urged  that  the  narrow  bays  of  the  coast 
of  Maine  correspond  to  the  fiords  of  Scandinavia  and  prove  that  the  land 
formerly  stood  at  a  higher  level  than  at  present.  These  bays  were  once 
valleys  of  subaerial  erosion,  now  in  part  submerged.  The  obvious  conclu- 
sion is  that  the  only  Tertiary  beds  likely  to  be  found  are  those  which  may 
have  been  deposited  in  fresh-water  lakes.  So  far  as  our  present  knowledge 
extends,  it  must  be  admitted  that  no  lake  or  river  drift  of  the  geological 
ages  immediately  preceding  the  coming  of  the  ice-sheet  has  escaped  the 
terrible  ordeal  of  ice.  Peats,  soils,  vegetable  mold,  and  the  bones  of  land 
animals  must  have  abounded,  but  they  were  either  removed  entirely  beyond 
the  State  or  were  crushed  to  powder  and  so  incorporated  with  the  rest  of 
the  till  that  no  one  has  been  able  to  recognize  them.  But  negative  evidence 
must  not  be  accepted  as  conclusive.  That  such  sediments  have  not  been 
found  by  no  means  proves  they  do  not  exist  and  may  not  yet  be  discovered. 
But  while  sedimentary  rocks  of  the  ages  immediately  preceding  the 
coming  of  the  Ice  age  have  not  been  found,  I  have  noted  many  instances 
of  rock  weathered  in  preglacial  time.  One  of  the  most  instructive  of  these 
is  at  one  of  the  slate  quarries  of  Brownville.  Most  of  the  rock  was  planed 
by  the  ice  to  a  very  level  surface.  In  the  midst  of  the  glaciated  surface 
was  a  depression  showing  a  U-shaped  cross  section.  This  Avas  probably  a 
valley  transverse  to  the  section,  but  its  true  shape  could  not  be  determined. 
The  depression  was  about  6  feet  wide  and  4  feet  deep.  The  upper  and 
central  parts  of  the  depression  were  filled  with  the  clayey,  bluish-gray  till 
characteristic  of  the  slate  region,  while  in  the  bottom  next  the  rock  was  a 
rather  pale,  brownish-red  earth,  mixed  with  fractured  and  weathered  slate. 
Some  of  the  nearly  vertical  cleavage  laminte  of  the  slate  had  weathered 
away  or  fallen  to  pieces,  leaving  the  more  enduring  lamina?,  projecting  into 
the  reddish  earth  from  1  to  4  or  even  6  inches,  thus  forming  a  very  rough 
and  serrate  surface.  This  depression  was  cut  across  by  the  quarry  excava- 
tion, and  at  the  depth  of  a  few  feet  below  the  depression  the  slate  appeared 
as  sohd  as  the  rest  of  the  quarry.  Hence  there  was  no  reason  to  suspect 
the  slate  of  being  unusually  soft  and  easily  weathered  or  decomposed  by 
waters  beneath  the  till.     Besides,  the  till  was  compact  and  unstained  by 


GLACIAL  DEPOSITS.  29 

percolating  waters.  As  elsewhere  stated,  this  roofing  slate  resists  weather- 
ing to  a  remarkable  degree.  All  the  circumstances  make  it  certain  that  so 
gi^at  an  amount  of  weathering  as  is  shown  by  the  slate  in  the  bottom  of 
this  depression  could  have  been  accomphshed  only  in  the  long  eons  of  pre- 
glacial  time.  The  bronwish  mass  in  the  bottom  of  the  depression  is  a 
residual  earth,  a  soil  of  preglacial  weathering.  This  subject  will  be  refen-ed 
to  hereafter. 

GliACIAL  DEPOSITS. 

THE    TILL. 

Resting  upon  the  glaciated  rock  (or  here   and  there  upon  the  small 
areas  of  nonglaciated  rock  weathered  in  preglacial  time)  is  the  till.     It  is 
an  endless    study.     So  varied    are    its  forms   and    developments   that  no 
attempt  can  be  made  within  the  space  allotted  to  this  portion  of  our  subject 
to  do  more  than  refer  to  those  properties  especially  related  to  the  subject 
of  the  glacial  gravels.     At  the  present  time  we  do  not  need  to  theorize  ^ 
concerning  the  existence  of  a  great  body  of  land    ice   over  northeastern 
North  America.     Assuming  that  the  area  of  Maine  was  covered  by  a  series 
of  ice  fields  that  were  practically  confluent,  so  as  to  form  an  ice-sheet,  we 
interpret  the  facts  as  to  the  till  in  accordance  with  the  glacial  hypothesis. 
The  names  given  to  the  till  in  Maine  deserve'  notice.     A  very  common 
name  for  the  formation  is  "hardpan."    This  no  doubt  refers  to  the  compact- 
ness of  the  formation  and  the  difiiculty  of  digging  into  it.    Another  common 
name  is  "pin  gravel,"  though  the  same  name  has  also  been  applied  to  any 
recent  conglomerate  or  water-washed  gravel  cemented  into  a  firm  rock  by 
carbonate  of  lime  or  by  iron  oxides  or  hydi-ates.     The  till  usually  contains 
many  stones  and  bowlders  of  all  sizes,  and  a  soil  composed  of  weathered 
till  is  commonly  known  as  "hard,  rocky  land,"  or  as  "rocky,  upland  soil." 
It  is  often  called  "hard-wood  soil,"  also  "orchard  land."     It  is  unfortunate 
that  the  term  "  gravel"  is  so  often  associated  with  the  till.     In  Maine  when 
soil  is  described  as  "gravelly,"  in  most  cases  it  is  meant  that  the  soil  is 
composed  of  till.     "Gravelly  loam"  almost  always  means  till,  but  some- 
times it  means  a  thin  stratum  of  marine  clay  overlying  and  partially  mixed 
with  true  water-assorted  and  rounded  gravel.     Many  know  the  formation 
as  the  ' '  bowlder  clay."     To  apply  the  terms  ' '  gravel "  or  ' '  clay  "  to  the  till  is 
a  fruitful  source  of  confusion,  causing  the  till  to  be  confounded  with  water- 


30  GLACIAL  GRAVELS  OF  MAINE. 

washed  gravel  on  the  one  side  and  with  sedimentary  clay  containing  bowl- 
ders on  the  other.  The  term  "bowlder  clay"  may  still  have  its  uses,  to 
describe  certain  disputed  formations,  but  in  New  England  it  ought  to  be 
replaced  by  the  word  "till."  This  word  is  short,  convenient,  and  implies 
no  theory  either  as  to  the  composition  or  the  origin  of  the  deposit.  The 
till  constitutes  what  was  known  to  the  older  geologists  as  the  "drift"  or 
"unmodified  drift." 

In  Maine  the  most  constant  cliaracteristic  of  the  till  is  that  it  is  com- 
posed of  drift  fragments  of  all  sizes,  from  the  finest  particles  of  clay  and 
rock  flour  up  to  the  largest  bowlders,  all  indiscriminately  mixed  together  in 
a  pellmell  mass,  except  that  the  lower  layers  contain  more  fine  matter  than 
the  upper  and  a  much  larger  proportion  of  distinctly  scratched  or  glaciated 
stones.  In  the  area  of  sedimentary  rocks  in  the  northeastern  part  of 
Aroostook  County  the  till  consists  almost  wholly  of  sand  and  clay,  most 
of  the  larger  stones  having  been  broken  into  their  constituent  grains  or 
ground  into  powder,  so  as  to  resemble  a  soil  of  preglacial  weathering,  and 
over  large  areas  bowlders  are  almost  unknown.  Although  almost  all  of 
the  till  has  drifted  toward  the  south  and  east,  the  distance  traveled  varies 
greatly.  On  Matinicus  Island  I  found  fossiliferotis  bowlders  of  Oriskany 
sandstone  which  must  have  traveled  140  or  more  miles.  By  count  of  the 
stones  large  enough  to  be  plainly  recognized  lithologically,  I  have  found 
that  by  far  the  greater  number,  especially  of  those  in  the  lower  part  of 
the  till,  were  derived  from  rocks  not  many  miles  away.  Repeatedly  the 
lower  till  has  been  seen  to  be  derived  chiefly  from  local  rock,  while  the 
upper  layers  were  derived  from  a  rock  that  outcropped  not  far  north.  On 
the  other  hand,  I  have  sometimes  found  near  the  bottom  of  the  till  much 
matter  from  a  distance.  Apparently  the  relative  proportions  of  near-  and 
far-traveled  matter  in  the  till  vary,  but  I  have  been  unable  to  discover  the 
laws  and  causes.  Sometimes  I  have  suspected  that  the  till  of  two  diff"erent 
glacial  periods  is  mixed,  but  have  not  been  able  to  find  the  necessary  field 
evidence.  That  the  character  of  the  till  changes  rapidlj^  as  we  pass  from 
slaty  into  schistose  or  granitic  areas  is  proved  not  only  by  count  of  frag- 
ments but  also  by  the  general  appearance  and  the  physical  properties  of 
the  soil,  and  often  by  the  vegetation.  The  greater  part  of  the  till  of  Maine, 
and  especially  the  large  bowlders,  must  on  the  average  have  drifted  but  a 
few  miles. 


GLACIAL  DEPOSITS.  31 

DISTEIBUTION   OF   THE   TILL, 

The  depth  of  the  till  varies  greatly.  Numerous  small  areas  are  bare  of 
it.  More  often  these  bare  places  are  in  the  valleys  or  on  the  tops  of  hills, 
■  especially  in  the  slaty  regions.  No  account  is  here  taken  of  the  areas  of  bare 
ledges  near  the  sea,  denuded  by  the  waves,  or  of  steep  hillsides,  denuded  by 
landslides.  In  many  places  bowlders  are  arranged  in  trains,  presenting  the 
appearance  of  the  moraines  of  modern  valley  glaciers.  I  have  elsewhere 
described  several  terminal  moraines,  most  of  which  appear  to  have  been 
foi'med  in  the  sea  at  the  extremity  of  the  ice  at  a  time  when  the  ocean  stood 
at  a  higher  level  than  now.  So  also  there  are  masses  of  till  of  various  shapes, 
mostly  short  i-idges  and  irregular  heaps,  found  in  low  depressions  of  the 
higher  east-and-west  ranges,  or  bordering  these  passes.  They  are  more 
numerous  on  the  north  than  on  the  south  slopes  of  the  passes.  Such  passes 
and  low  cols  would  for  a  time  during'  the  decay  of  the  ice-sheet  afford  exit 
southward  for  tongues  of  ice  after  the  glacier  had  become  too  thin  to  permit 
flow  over  the  higher  hills.  These  heaps  have  not  so  steep  slopes  as  the  ordi- 
nary terminal  and  lateral  moraines  of  mountain  glaciers  have,  and  the  shapes 
of  the  morainal  masses  deposited  by  glaciers  bearing  matter  which  fell  on 
them  from  above  are  evidently  different  from  those  into  which  the  moraine 
stuff  was  incorporated  from  beneath,  if  we  except  tlie  extreme  terminal 
moraine.  It  is  an  interesting-  study  to  determine  whether  thick  masses  of 
englacial  till  can  be  accumulated  within  the  ice  by  ice  movements.  The 
term  moraine  was  first  definitely  applied  to  masses  that  accumulated  on  the 
surface  or  at  the  extremity  of  the  ice.  It  has  also  been  applied  to  the  mat- 
ter beneath  the  ice.  Can  it  properly  be  applied  to  a  mass  of  the  ground 
moraine  of  unusual  thickness  or  to  similar  masses  of  englacial  till  ?  In  this 
report  I  have  not  applied  the  term  moraine  to  masses  of  till  unless  they 
present  the  external  and  internal  characters  of  the  moraines  found  on  the 
surface  or  at  the  extremities  of  ordinar}^  living  glaciers;  except  that  ground 
moraine  is  used  as  a  generic  term  to  indicate  the  whole  of  the  subglacial  till, 
but  not  individual  masses  or  accumulations  of  it. 

In  the  hilly  parts  of  the  State  the  phenomena  of  "crag  and  tail"  are 
well  exhibited.  This  term  refers  to  the  accumulation  of  till  which  collected 
in  the  lee  south  of  projecting  hills,  especiall}^  conical  peaks.  These  accu- 
mulations consist  of  ridges  or  deep  sheets  of  stony  till,  generally  of  loose 
structure  and  rather  easily  eroded  by  sj^rings  and  rains. 


32 


GLACIAL  GRAVELS  OF  MAINE. 


On  the  northern  and  northwestern  slopes  of  rather  high  hills  deep 
sheets  of  fine,  clayey  till  abound.  The  till  is  in  general  thinner  on  the 
hilltops  and  in  the  valleys  than  on  the  intermediate  slopes.  This  fact, 
combined  with  the  rounded,  flowing  outlines  of  the  mass,  gives  to  these 
hillside  accumulations  of  till  a  shape  somewhat  lenticular  in  cross  section, 
but  they  often  extend  for  miles  along  the  sides  of  a  ridge. 

In  the  southwestern  part  of  the  State,  hills  of  mammillary  or  lenticular 
shape  abound,  but  they  are  not  so  large  oi-  numerous  as  the  lenticular  hills 


Fig.  2.— Section  ; 


deep  lenticular  sheet  of  till ;  Keuta  Hill,  Eeailfleld. 


of  till  so  abundant  in  certain  parts  of  New  Hampshire  and  ]\Iassachusetts. 
Sometimes,  as  at  the  eastern  end  of  Portland,  there  is  a  rock  nucleus,  above 
and  around  which  the  till  collected ;  l3ut  more  often  no  such  nucleus  appears 
anywhere  on  the  surface,  and  if  it  exists  it  must  be  of  small  size  as  com- 
pared with  the  whole  hill. 

Professor  Hitchcock  and  Mr.  Warren  Upham  named  them  "lenticular 
hills"  in  the  reports  of  the  New  Hampshire  survey.  Similar  masses 
appear  to  have  previously  received  the  name   of    "drumlins"  in  Great 

Britain  and  Ireland,  and  this 
name  is  now  generally  adopted. 
In  Maine  the  drumlins  of  the 
southwestern  coast  region  are 
mostly  roundish  or  slightly  elon- 
gated. Back  farther  from  the 
coast,  and  especially  in  the  eastern  part  of  the  State,  there  are  many  which 
take  the  form  of  ridges,  sometimes  a  mile  or  more  long,  with  arched  cross 
section,  like  the  osars.  They  contain  no  water-washed  material  like  the 
osars,  and  are  substantially  parallel  with  the  glacial  scratches  of  the  region. 
Often  I  have  traveled  a  long  distance  in  the  wilderness  in  search  of  a 
"horseback"  which  had  been  described  to  me,  and  which  I  anticipated  find- 
ing to  be  an  osar,  only  to  find  it  a  mass  of  till.  Such  a  ridge  has  been  cut 
by  the  Penobscot  River  at  the  mouth  of  South  Twin  Lake.     The  local 


-Section  ;tcroS8  Muujoy  Hill,  Portland, 
lenticular  mass  of  till,  and  tliat  liy  glacial  j 


erlaiu  by 


UPPER  AND  LOWER  TILL.  33 

rock  is  slate.  The  till  next  the  rock  is  intensely  tough  and  clayey,  being 
mostly  derived  from  the  clay  slate.  The  ridge  proper  rests  on  this  sheet 
and  contains  a  large  proportion  of  granitic  matter  derived  from  the  granite 
outcrop  near  Mount  Katahdin.  The  ridge  has  a  sort  of  lamination,  as  if 
accumulated  in  successive  layers  parallel  with  its  arched  surface;  yet  it  is 
true  till  and  at  the  exposures  examined  contains  no  sedimentary  matter. 
Near  East  Vassalboro  and  elsewhere  are  a  few  symmetrical  cones  which  on 
the  surface  are  composed  of  sandy  till.  They  are  found  suspiciously  near 
the  discontinuous  kame  systems,  and  this  suggests  genetic  relationship  with 
the  conical  and  lenticular  kames.  As  suggested  elsewhere,  a  glacial  stream 
that  plunges  down  a  crevasse  will  enlarge  its  shaft  at  the  bottom  and  form 
a  conical  cavity,  in  which  a  conical  kame  will  collect  if  the  stream  brings 
down  coarse  sediment.  If  the  stream  should  for  some  reason  cease  to  flow 
at  this  place,  it  is  possible  that  till  might  subsequently  collect  in  the  ice 
cavity  around  the  original  kame  as  a  nucleus;  and  if  little  or  no  gravel  col- 
lected in  the  cave,  still  it  might  in  some  way  become  filled  with  till  after  the 
flow  of  the  stream  ceased. 

Irregular  heaps  and  ridges  of  till,  which  appear  to  be  mostly  composed 
of  englacial  matter,  abound  in  all  parts  of  the  State.  When  these  are 
mapped  and  masses  of  the  ground  moraine  distinguished  from  the  englacial 
till,  it  will  be  possible  to  write  out  almost  the  whole  history  of  the  ice 
movements.  The  till  is  more  unequally  distributed  in  the  granitic  and 
coarsely  schistose  regions  than  in  the  areas  of  slates  and  sedimentary 
rocks,  and  its  distribution  is  more  irregular  near  the  coast  than  in  the 
interior. 

THE    UPPEB    AND   LOWER    TILL. 

The  upper  layers  of  the  till  are  less  compact  than  the  lower,  perhaps 
owing  in  part  to  the  heaving  of  the  frost.  No  doubt  frost  has  in  some 
cases  brought  up  bowlders  toward  the  surface,  and  this  partly  accounts  for 
the  fact  that  most  of  the  larger  bowlders  are  found  on  or  near  the  surface, 
but  only  partly,  for  in  the  granitic  regions  bowlders  are  often  piled  one 
above  another  in  such  a  manner  that  the  frost  can  not  have  changed  their 
relative  positions,  and  here  the  larger  bowlders  are  more  often  at  the  top. 

The  most  probable  interpretation  of  the  facts  is  that  the  finer  and  more 
intensely  glaciated  lower  portion  of  the  till  was  deposited  in  its  present 
MON  xxxiv 3 


34  GLACIAL  GRAVELS  OF  MAINE. 

position  and  shapes  beneath  the  ice  as  a  ground  moraine  proper,  while  the 
upper  part  of  the  till,  of  less  compact  structure,  less  marked  glaciatiou, 
and  containing  the  largest  bowlders,  is  composed  of  matter  which  was 
distributed  throughout  the  lower  portion  of  the  ice.  The  classification  of 
the  till  into  a  lower  and  an  upper  member,  early  adopted  by  Professor 
Hitchcock  in  the  New  Hampshire  geological  reports  (substantially  that 
proposed  by  Torell),  seems  to  have  a  basis  in  fact.  At  one  time  I  thought 
it  possible  to  distinguish  in  the  field  between  the  ground  moraine  and  the 
upper  till,  but  subsequent  observations  have  shown  many  places  where  this 
is  difficult,  if  not  impossible.  Indeed,  it  appears  probable  that  the  two 
formations  often  blend  with  each  other,  so  that  there  is  no  sharp  line  of 
demarcation  between  them. 

It  is  well  known  that  in  the  Mississippi  Valley  there  are  two  or  more 
layers  of  till  separated  by  strata  containing  peat  and  other  traces  of  a 
warm  interglacial  period.  No  such  signs  of  two  general  glaciations  have 
yet  been  found  in  Maine.  The  few  facts  that  indistinctly  point  that  way 
seem  as  yet  to  be  capable  of  other  interpretations,  although  during  the 
final  melting  there  may  have  been  alternate  retreat  and  advance  near  the 
ice  margin. 

SEDIMENTS    TRANSPORTED    BY    GLACIAL    STREAMS. 

These  deposits  of  water-assorted  drift  have  attracted  attention  all  over 
the  world  wherever  they  are  found.  Their  most  obvious  characteristics  are 
the  following: 

External  forms  of  deposits. — Tlic  simplest  fomi  is  that  of  a  cone,  dome,  or 
hummock,  and  we  find  all  transitions  between  these  forms  and  the  elon- 
gated, two-sided  ridge.  When  enlarged  on  all  sides,  the  dome  becomes  a 
rather  round  plain  with  flattish  top.  The  single  ridge  may  fork  into  two 
ridges,  which  soon  come  together  again,  thus  inclosing  a  basin  or  kettle- 
hole,  which  not  infrequently  contains  a  lakelet;  or  it  may  divide  into  a 
large  number  of  branches  which  are  themselves  connected  by  transverse 
ridges,  the  whole  forming  a  plexus  of  ridges  inclosing  depressions  of  all 
shapes.  Such  networks  have  been  called  reticulated  ridges  by  Prof.  N.  S. 
Shaler.  The  depressions  inclosed  between  these  ridges  are  of  various 
shapes  and  have  received  many  names,  such  as  basins,  sinks,  funnels,  kettle- 
holes,  punch  bowls,  hoppers,  Roman  theaters. 


p      E 


Lz 


M^i&i;)^. 


NAMES  OF  GLACIAL  DEPOSITS.  35 

Names. — TliGse  gTavel  deposits  have  such  curious  and  distinctive  shapes 
tliat  they  have  received  local  names  wherever  they  occur.  The  Scandina- 
vian osars,  the  Irish  eskers  (or  eskars,  or  eschars),  and  the  Scotch  kames 
are  supposed  to  be  the  equivalents  of  the  gravel  ridges  here  described,  or 
nearly  related  to  them.  These  deposits  contain  matter  of  various  sizes, 
fi-om  fine  clay  to  large  bowlders,  but  gravel  is  by  far  the  most  abundant. 
I  have  found  the  term  glacial  gravel  a  convenient  general  title  for  describing 
every  kind  of  coarse  sedimentary  formation  which  was  deposited  by  glacial 
streams.  The  term  has  the  disadvantage  of  implying  a  theory  as  to  the 
origin  of  these  sediments,  and  it  does  not  describe  their  composition  in  all 
cases,  yet  it  is  often  convenient  as  a  generic  name  when  there  is  doubt 
what  specific  name  should  be  given  to  a  certain  deposit,  whether  kame, 
osar,  etc. 

In  Maine  these  deposits  have  received  many  local  names.  The  most 
common  name  is  "horseback,"  but  this  name  is  also  applied  to  a  hill  or 
ridge  of  any  other  kind  of  matei'ial,  whether  loose  material  or  solid  rock. 
They  are  also  known  as  "whalebacks"  and  "hogbacks."  Sometimes  one 
of  these  ridges  is  known  as  the  Ridge  (as  Chesterville  Ridge),  and  they  are 
not  infrequently  known  as  "windrows,"  "turnpikes,"  "back  furrows," 
"ridge  furrows,"  "morriners,"  and  sometimes  as  "hills."  Several  of  these 
ridges  used  to  be  known  as  "Indian  roads,"  because  Indian  trails  were 
made  on  top  of  them  in  the  midst  of  a  swampy  region.  In  one  place  a 
ridge  of  this  kind  was  called  the  "  Indian  railroad."  It  may  be  suspected 
that  those  who  gave  it  this  name  had  in  mind  certain  archeologists  who 
have  thought  that  the  osar  ridg-es  were  built  by  the  Indians.  It  would  cer- 
tainly be  remarkable  if  the  Penobscot  and  Passamaquoddy  Indians  or  their 
predecessors  had  been  so  industrious  in  former  ages  as  to  outdo  the  mound- 
builders  and  build  several  thousand  miles  of  these  embankments — embank- 
ments far  surpassing  in  size  all  the  mounds  of  the  Mississippi  Valley 
and  the  railroads  of  Maine  combined.  Cones  of  glacial  gravel  are  fre- 
quently known  as  "pinnacles,"  "hills,"  "peaks,"  or  even  as  "mountains." 
Broad,  flat-topped  ridges  have  attracted  much  less  attention  than  the  two- 
sided  ridges  and  the  cones ;  yet  many  of  them  are  locally  known  as 
"plains,"  and  this  is  the  common  name  in  Maine  for  a  plexus  of  the  reticu- 
lated ridges,  oi'  for  any  broad  mass  of  sand  and  gravel,  especially  when 
overgrown  by  blueberries  and  other  bushes. 


36  GLACIAL  GEAVELS  OF  MAINE. 

Briefly  stated,  the  glacial  gravels  are  found  in  the  form  of  every  kind 
of  ridge,  terrace,  cone,  dome,  heap,  mound,  and  plain  into  which  loose, 
water-washed  matter  can  be  piled,  and  with  both  steep  and  gentle  slopes. 

Topographical  relations. — Generally  tliese  deposits  of  water-assorted  sand  and 
gravel  are  heaped  up  above  the  surrounding  level.  They  also  take  the 
form  of  flattish-top  terraces  on  hillsides,  or  they  may  fill  a  valley  from  side 
to  side  as  a  plain  of  level  cross  section  but  inclined  longitudinally  at  the 
same  slope  as  the  valley.  They  often  form  long  systems  with  average 
trend  from  north  to  south  and  nearly  parallel  with  the  glaciation.  Some- 
times they  are  found  in  the  valleys  of  existing  streams,  but  more  often 
where  no  ordinary  surface  stream  larger  than  a  mere  brook  can  ever  have 
flowed,  even  in  the  time  of  the  most  violent  floods.  Many  of  the  shorter 
systems  are  only  from  100  to  400  feet  above  the  sea  at  their  northern 
extremities,  while  the  longer  systems  oi'iginate  at  the  north  at  elevations  of 
700  to  1,600  feet,  a  few  ridges  nearly  2,000  feet  high  being  known.  The 
northern  ends  of  the  distinct  systems  are  higher  than  the  southern  ends, 
but  the  gravels  do  not  follow  a  uniform  slope.  The  map  shows  well  how 
often  they  leave  the  valley  of  a  stream  and  pass  over  a  divide  or  low  col 
into  the  valley  of  another  stream.  In  so  doing  they  not  only  rise  above 
the  average  grade  line  of  the  system,  measured  from  one  extremity  to  the 
other,  but  they  also  rise  in  actual  elevation  above  the  sea.  Throughout  the 
greater  part  of  the  State  I  do  not  know  of  any  of  the  systems  crossing 
hills  more  than  200  feet  higher  than  the  valleys  lying  to  the  north  of  them. 
But  in  the  southwestern  part  of  the  State  they  repeatedly  go  up  and  over 
hills  200  to  250  feet,  in  one  case  400  feet,  high  (measured  on  the  north). 
Since  the  height  of  the  hills  which  the  gravel  systems  could  surmount  was 
limited,  they  always  penetrate  high  ranges  of  hills  by  low  passes.  These 
passes  are  not  always  the  lowest  that  could  have  been  chosen,  nor  are  they 
always  the  most  direct.  Probably  in  the  larger  number  of  cases  the  gla- 
cial rivers  took  the  best  roiites  for  getting  from  one  end  to  the  other,  taking 
both  grade  and  du-ectness  into  account. 

An  experienced  engineer  wishing  to  construct  a  railroad  between  the 
termini  of  the  longer  systems  as  economically  as  possible,  by  the  shortest 
route  consistent  with  the  minimum  amount  of  rise  and  fall,  would  in  a  sur- 
prising number  of  cases  find  himself  following  the  same  route  as  the  gravel 
.systems.     A  good  topog'raphical  or  relief  map  of  the  State  would  reveal 


SEDIMENTS  TRANSPOETED  BY  GLACIAL  STREAMS.  37 

this  fact  much  more  plainly  than  the  existing  maps  do.  Where  these  gravel 
ridges  cross  a  level  and  swampy  region,  they  often  form  a  remarkable  fea- 
ture of  the  landscape.  In  many  cases  they  form  natural  roadways  across 
the  swamps  and  have  been  utilized  for  this  purpose  by  both  Indians  and 
whites.  When  an  explorer  has  followed  one  of  these  great  embankments 
for  50  or  100  miles,  crossing  rivers  and  valleys,  climbing  over  hills,  now 
skirting  hillsides  far  above  the  valleys,  now  meandering  across  a  plain  where 
nothing  now  exists  to  cause  meanderings,  and  bending  abruptly  in  order  to 
penetrate  some  low  pass — by  the  time  he  has  seen  all  this  and  noted  how, 
within  certain  limits,  these  gravel  systems  disregard  the  surface  features  of 
the  land,  he  will  be  ready  to  admit  the  utter  impossibility  of  accounting  for 
the  existence  of  water-rolled  gravels  in  such  situations  by  any  form  of 
fluviatile,  marine,  or  lacustrine  agency,  or  by  any  known  means  except  by 
streams  confined  between  walls  of  ice  that  have  now  disappeared. 

Sizes  and  lengths. — The  uarrow  tw^o-sided  ridges  are  sometimes  barely  3 
feet  high  and  three  or  four  times  as  broad,  and  all  sizes  exist  up  to  100  or 
more  feet  high,  with  corresponding  breadth.  The  broader  ridges  or  plains 
vary  in  height  to  a  maximum  of  about  150  feet.  The  deepest  kettlehole 
measured  was  about  100  feet  in  de^^th.  Many  of  the  ridges  are  barely 
wide  enough  for  a  road  on  the  top,  while  massive  plain-like  ridges  are  found 
which  are  from  one-eighth  mile  to  more  than  a  mile  wide.  The  plains  of 
reticulated  ridges  are  sometimes  3  or  4  miles  wide,  and  the  marine  delta- 
plains  are  still  broader.  Where  the  gravels,  when  mapped,  are  plainly 
seen  to  be  arranged  in  lines  along  routes  that  do  not  cross  very  high  hills, 
they  are  assigned  to  the  same  system.  The  gravels  of  a  single  system  are 
supposed  to  have  been  deposited  by  a  single  glacial  river.  The  gravel  is 
not  continuous  throughout  the  course  of  a  system.  Sometimes  the  gaps 
are  due  to  erosion  of  the  gravel,  but  more  often  they  are  due  to  failure  of 
the  glacial  river  to  deposit  gravel  throughout  its  whole  course.  The  gaps 
are  usually  less  than  one-half  mile  across,  but  in  some  cases  2  or  3  miles. 
When  gravel  deposits  are  separated  by  such  long  gaps,  I  have  never  assigned 
them  to  one  system  without  special  proof  according  to  the  principles  laid 
down  here  and  elsewhere.  Several  of  the  systems  are  100  or  more  miles 
in  length. 

Branchings. — Tlic  brauchcs  of  the  longer  gravel  systems  may  be  classified 
as  follows:    (1)    Tributary  branches.     The  map  shows  that  many  of  the 


38  GLACIAL  GKAVELS  OF  MAINE. 

systems  receive  branches  which  converge  toward  the  south,  like  the  tribu- 
taries of  ordinary  rivers  flowing-  in  that  direction.  This  sort  is  especially 
noticeable  in  the  eastern  part  of  the  State.  (2)  Delta  branches.  Systems 
often  divide  into  two  or  more  branches  diverging  toward  the  south,  like  rivers 
at  their  deltas.  The  most  remarkable  examples  of  this  class  of  divergent 
branches  are  found  in  the  southwestern  part  of  the  State.  When  both 
kinds  of  branches  are  found  in  the  same  system,  the  tributaries  are  toward 
the  northern  end  of  the  system  and  the  delta  branches  toward  the  southern. 
Assuming  that  the  glacial  gravels  were  deposited  by  glacial  streams,  we 
see  that  these  streams  in  many  respects  conform  to  the  habits  of  ordinary 
surface  streams,  though  their  causes  and  environment  were  different. 

Meanderings. — The  map  shows  that  the  longer  systems  follow  tortuous 
courses.  Many  of  these  deflections  were  taken  because  of  the  surface 
features  of  the  land,  such  as  the  positions  of  the  high  hills  and  low  passes. 
There  are  also  many  short  zigzags  which  plainly  resemble  the  meandering 
of  streams,  yet  they  are  found  in  level  regions  where  there  are  no  surface 
featui'es  to  cause  them.  Apparently  many  of  the  minor  curves  and  mean- 
derings of  the  glacial  rivers  were  caused  by  conditions  of  the  ice  which 
did  not  depend  on  the  land  surface  beneath  the  glacier. 

Directions  of  their  courses. — Tlie  average  directlou  of  the  gravel  systems  is  a 
little  east  of  south,  varying-  all  the  way  from  southwest  to  south  and  east, 
and  in  a  few  cases  for  a  short  distance  even  a  little  north  of  east.  T\Tiile 
there  is  often  a  tendency  to  follow  the  lines  of  glaciation,  yet  there  are 
many  notable  exceptions.  Thus,  in  eastern  Maine  there  is  a  remarkable 
convergence  of  several  gravel  systems  toward  Jonesboro  and  Columbia 
Falls.  There  is  a  convergence  of  the  glacial  scratches  toward  the  same 
points,  but  it  is  not  so  great  as  that  of  the  gravels.  The  convergence  of 
the  gravel  systems  and  that  of  the  scratches  are  nearly  uniform  toward 
Belfast  Bay.  Most  of  the  discontinuous  systems  are  nearly  parallel  with 
the  scratches.  At  Danforth  Village  the  glacial  river  abandoned  a  low  pass 
and  took  a  higher  one  more  nearly  parallel  with  the  glaciation.  On  the 
other  hand,  there  is  but  little  convergence  of  scratches  toward  Penobscot 
Bay;  yet  several  long  glacial  rivers  which  were  widely  separated  at  their 
northern  ends,  united  to  form  a  single  river  a  few  miles  north  of  the  bay. 
The  Holden-Bucksport  and  the  South  Albion-China  systems  both  take  a 
southwest  course  on  account  of  high  ranges  of  hills.     At  North  Waterford 


COMPOSITION  AND  STRUCTURE  OF  GLACIAL  DEPOSITS.  39 

n  glacial  river  at  one  time  flowed  southwest  to  Lovell  and  at  another  time 
followed  the  valley  of  Crooked  River  for  a  few  miles  east  and  south.  So 
also  at  the  south  end  of  Hogback  Mountain  Pass,  in  Montville,  a  glacial 
river  took  two  diverging  courses,  either  simultaneously  or  at  different  times. 
In  both  of  these  cases  the  larger  flow  was  along  the  southwestern  course 
and  over  hills  of  moderate  height,  while  the  lesser  flow  took  place  down 
valleys  of  natural  drainage  and  more  nearly  parallel  with  the  glaciatiou. 

Composition. — ^These  deposits  are  nonnally  composed  of  water-assorted 
sediments.  The  fragments  vary  in  size  all  the  way  from  the  finest  clay  up 
to  sand,  gravel,  pebbles,  cobbles,  bowlderets,  and  bowlders  3  to  4  and  even 
5  feet  in  diameter.  Gravel  is  by  far  the  most  abundant  material.  Clay 
seldom  appears  except  as  thin  beds  in  the  midst  of  the  coarser  sediments. 
Occasionally  there  are  masses  in  these  deposits  closely  resembling  till,  yet 
in  general  the  finer  matter  has  so  plainly  been  washed  out  that  there  is  no 
difficulty  in  distinguishing  them  from  the  unmodified  till.  They  are  in  fact 
the  till  more  or  less  water  washed,  i.  e.,  the  residue  left  after  the  fine  parts 
of  the  till  have  been  removed  by  glacial  water. 

Internal  structure. — Most  kames  and  osars  are  stratified  in  a  very  complex 
manner.  Both  transverse  and  long'itudinal  sections  of  the  kame  ridge  will 
fi'equently  show  cross  bedding.  In  the  longer  ridges  the  oblique  laminae 
generally  dip  toward  the  south  and  obliquely  outward  toward  the  sides  of 
the  ridge,  so  that  in  cross  section  the  strata  appear  to  be  arched.  In  the 
broad  level-topped  plains  the  stratification  is  often  nearly  horizontal.  The 
strata  are  sometimes  inclined  at  very  high  angles,  almost  vertical,  but  only 
locally  over  small  areas,  so  far  as  I  have  observed.  In  some  cases  the 
lines  of  stratification  are  curved  and  twisted,  probably  the  result  of  dis- 
tortion since  the  original  deposition.  In  a  dome  or  cone  the  stratification 
is  often  quaquaversal,  and  sometimes  monoclinal,  either  parallel  or  trans- 
verse to  the  gravel  system,  as  if  the  deposition  took  place  from  the  top  of 
the  cone  downward  in  all  directions,  or  sometimes  only  at  one  side  of  the 
chamiel  of  the  glacial  river. 

In  some  osars  a  portion  of  their  length  shows  no  lines  of  stratification. 
The  finer  ddbris  has  been  washed  out  of  them,  and  the  stones  even  in  the 
pellmell  portions  are  plainly  rounded  by  water.  It  is  more  probable  that 
the  present  pellmell  condition  of  tlie  sediments  is  due  to  the  obliteration  of 
an   original    stratification  by  unequal   and   irregular  settling  and  sliding 


40  GLACIAL  GRAVELS  OP  MAINE. 

rather  than  to  any  freak  of  sedimentation  whereby  no  stratification  was 
produced.  If  the  sediment  was  deposited  upon  the  ice  it  would  naturally 
lose  its  structure  during  the  melting  of  the  subjacent  ice. 

Shapes  of  the  constituent  fragments. — In  the  glacial  gravcls  we  find  all  degrees  of 
water  wear.  In  some  of  the  shorter  systems  and  toward  the  northern  ends 
of  many  of  the  longer  systems  the  stones  and  grains  are  but  barely  pol- 
ished at  the  angles  and  difi^er  so  little  from  till  in  then-  shapes  that  the  mass 
may  be  regarded  as  a  slightly  water-washed  till.  On  the  other  hand,  most 
of  the  stones  and  grains  of  the  kames  and  osars  show  a  very  large  amount 
of  attrition  and  rolling  and  are  very  much  rounded. 

Direction  and  distance  of  glacial-gravel  transportation. In     Small     COnCS     aud     domCS     tllC 

lines  of  lamination  frequently  dip  outward  in  all  directions,  as  if  the  water 
came  from  above  at  the  center  of  the  cone  and  flowed  downward  and  out- 
ward on  all  sides.  In  the  case  of  ridges,  the  frequency  of  transverse  and 
oblique  dip  shows  that  much  of  the  drift  w^as  first  at  the  top  aiid  center  of 
the  ridge,  and  thence  w^as  washed  partly  lengthwise  of  the  ridge  and  partly 
sidewise  or  downward.  At  the  fan-shaped  delta  localities,  where  glacial 
streams  flowed  into  broadened  channels,  or  into  glacial  lakes,  or  the  sea, 
there  were  many  local  whirls  and  eddies  where  kame  matter  was  transported 
northward  for  short  distances.  With  the  exception  of  these  accidents  of 
water  motion  within  the  tortuous  channels  of  the  glacial  rivers  or  near  their 
mouths,  the  proof  is  in  most  cases  conclusive  that  kame  and  osar  transpor- 
tation was  southward.  In  a  few  places  I  have  found  no  positive  proof  of 
the  direction  of  motion.  The  direction  of  flow  is  proved  by  the  following 
considerations:  The  prevailing  southward  dip  of  the  laminse  of  the  ridges; 
the  higher  elevation  at  the  north  end  of  the  systems;  the  direction  of  the 
flow  of  the  glacier  and  the  position  of  the  terminal  moraines;  and  directly 
and  positively  by  observations  on  the  osar  drift  itself  Where  an  osar  passes 
from  an  area  of  one  kind  of  rock  into  an  area  of  a  difi'erent  rock,  the  osar 
drift  changes  just  as  the  till  does,  but  not  so  abruptly;  it  is  thus  proved  that 
the  average  distance  of  transportation  was  greater  in  the  case  of  the  osars 
than  ill  the  case  of  the  till,  and  also  that  the  drift  was  in  the  same  direction. 
Proofs  of  this  are  given  elsewhere.  Naturally  when  one  sees  gravel  sys- 
tems going  up  the  northern  side  of  a  hill  to  a  height  of  200  feet  or  more, 
it  seems  incredible  that  a  stream  could  flow  southward  over  such  a  barrier. 
That  they  actually  flowed  over  such  barriers  is  strong  evidence   of  the- 


BEACH  AND  COVE  GRAVELS.  41 

existence  of  ice.  The  pressure  and  head  of  water  necessary  to  drive  streams 
up  and  over  such  hills  could  be  secured  only  in  channels  or  tunnels  within 
the  ice. 

JNIARINB  DEPOSITS  AKD  GEOLOGIC AL  WORK  OF  THE  SEA. 

The  geological  surveys  of  both  Jackson  and  Hitchcock  presented 
abundant  proof  that  clays  and  sands  containing  marine  fossils  are  found  in 
Maine  far  above  the  present  level  of  the  sea.  Lists  of  fossils  were  pub- 
lished, and  these  were  afterwards  enlarged  by  Packard  and  Shaler.  Fossils 
from  these  beds  have  been  collected  by  numerous  observers,  including  Mr. 
C.  B.  Fuller  and  Dr.  AVilham  Wood,  of  Portland;  Prof.  C.  H.  Fernald,  of 
Orono ;  Prof.  L.  A.  Lee,  of  Brunswick,  and  Prof.  R.  Stanley,  of  Lewiston.  A 
fine  collection  of  these  fossils,  made  at  Gardiner  and  known  (from  the  donor) 
as  the  Allen  Collection,  is  now  in  the  cabinets  of  Bowdoin  College.  The 
highest  level  at  which  fossils  have  been  found,  so  far  as  known,  is  217  feet 
(Hitchcock's  report).  There  can  be  no  accurate  study  of  the  drift  without 
distinguishing  between  marine  and  glacial  gravels.  It  therefore  becomes 
necessary  to  describe  in  some  detail  the  nature  of  the  work  which  the  sea 
has  done  over  that  part  of  Maine  which  in  the  so-called  Champlain  time 
was  submerged  in  the  ocean. 

BEACH    AND    COVE    GRAVELS. 

At  hundreds  of  places  along  the  coast  I  have  examined  the  slopes  of 
the  higher  hills  for  traces  of  old  beaches.  For  the  same  purpose  many 
of  the  islands  were  visited,  the  most  important  of  which  lie  farthest  from 
the  coast,  viz,  Monhegan,  Matinicus,  and  Ragged  islands.  Isle  an  Haut,  and 
Mount  Desert. 

The  best  place,  perhaps,  to  begin  our  investigation  is  at  the  island  of 
Monhegan.  This  island  is  located  9  miles  off  the  mainland  at  Pemaquid 
Point,  is  surrounded  by  pretty  deep  water,  and  is  consequently  far  from 
sliore  ice  and  exposed  to  the  full  force  of  the  ocean.  The  central  parts  of 
the  island  form  a  sort  of  plateau,  from  which  several  small  hills  rise  to  a 
height  of  120  to  150  feet  above  the  sea.  The  marginal  slopes  are  rather 
steep  on  all  sides,  except  at  a  few  narrow  coves  and  on  the  west  side,  where 
there  is  a  small  sand  beach,  also  the  harbor,  partially  23rotected  by  the 
neighboring  island  of  Mananas.  The  island  is  about  2  miles  long  from 
northeast  to  southwest,  and  its  breadth  is  about  three-fourths  of  a  mile. 


42 


GLACIAL  GEAVELS  OF  MAINE. 


Its  longer  side  is  thus  presented  to  the  open  ocean  in  the  direction  from 
which  the  largest  storm  waves  come.  Considering  the  small  size  of  the 
island,  its  position  so  far  from  the  land,  and  the  exposure  of  its  flank  to  the 
storm  waves,  it  is  doubtful  if  any  place  can  be  found  on  the  whole  coast 
where  the  sea  could  act  to  better  advantage.  Here  we  may  know  what  the 
utmost  fmy  of  the  sea  could  accomplish,  remembering  that  when  the  ocean 
stood  at  higher  level  than  now  the  island  would  be  still  farther  from  the 
mainland  and  still  more  exposed  to  waves  from  every  direction. 

Except  near  the  harbor  and  at  a  few  small  coves,  the  island  is  bordered 
by  cliff's  of  erosion  at  the  present;  level  of  the  sea.  On  the  more  exposed 
(east  and  southeast)  sides  these  cliffs  vary  in  height  from  a  barely  percep- 
tible roughening  of  the  rock  to  30  feet,  and  in  a  few  places  thej  are  even 
higher.     They  show  the  irregular  and  honeycomb  appearance  character- 


FlG.  4. — Lougilndinal  section  of  cove  gravel. 


istic  of  the  clifP  of  wave  erosion.  In  a  few  places,  not  far  above  high  tide, 
quartz  veins  show  conchoidal  depressions  and  uneven  groovings,  due  to 
sand  carving  under  the  action  of  the  surf  At  the  head  of  one  of  the  coves 
are  several  potholes  10  to  15  feet  above  high  tide.  The  waves  become  nar- 
rowed, and  consequently  higher,  as  they  advance  up  the  cove.  They  rush 
swiftly  up  the  slope  at  the  end  of  the  cove  to  a  height  of  20  or  even  30  feet 
above  high  tide,  and  then  the  undertow  flows  swiftly  back.  Dming  this 
alternate  rush  of  water  in  opposite  directions  the  stones  and  bowlders  are 
set  whirling  in  any  depressions  there  may  be  in  the  rock,  and  thus  potholes 
are  in  time  eroded.  A  section  across  one  of  these  coves  or  small  bays 
shows  a  mass  of  beach  gravel  and  bowlders  occupying  the  bottom  of  the 
vallev  that  slopes  down  to  the  cove.  In  cross  section  the  top  of  the  beach 
matter  is  nearly  level.     A  longitudinal  section  shows  that  it  slopes  rather 


BEACH  AND  COVE  GRAVELS.  43 

steeply  up  from  the  sea  to  a  height  determined  by  the  waves,  while  at  the 
same  time  the  undertow  has  taken  a  portion  of  the  beach  matter  out  into  the 
sea,  as  shown  in  fig.  4. 

The  distance  the  finer  matter  is  drawn  back  into  the  sea  depends  on 
many  circumstances,  such  as  the  height  of  the  tides,  the  outline  of  the 
coast,  the  slope  of  the  shore,  the  depth  of  the  water,  etc.  When  the  slope 
is  sufficiently  gentle,  the  forward  push  of  the  breakers  is  greater  than  the 
backward  pull  of  the  undertow,  and  a  ridge  of  shingle  is  formed  across 
the  bays,  as  shown  in  fig.  6.  Such  ridges  are  named  sea  walls  in  Maine, 
and  are  common  on  the  exposed  coasts.  The  material  is  derived  ivoxu  the 
erosion  of  the  projecting  headlands  or  is  driven  up  from  the  sea  bottom 
when  the  slope  is  very  gradual.  Indeed,  there  is  always  a  sort  of  shelf  or 
terrace  near  low  tide,  where  the  force  of  the  undertow  is  checked  by  the 
sea,  even  in  the  steeper  coves.  If,  now,  the  slope  should  become  more 
gentle,  the  forward  push  of  the  waves  would  soon  change  the  terrace  into  a 


Sea/eye/. 


F[G.  5.— Transverse  «ectioii  of  f 

ridge  rising  above  the  land  back  of  it.  Such  are  the  beaches  of  the  glacial 
Lake  Agassiz,  as  described  by  Mr.  Warren  Upham,  and  the  old  beaches 
of  Lake  Ontario  observed  by  me  in  central  New  York.  Occasionally 
such  a  sea  wall  was  formed  in  Maine  in  the  period  when  the  sea  stood 
above  its  present  level,  though  the  ones  examined  by  me  were  neither  so 
high  nor  so  long  as  those  of  the  coast  to-day.  Having  the  form  of  an 
artificial  embankment  across  a  valley,  which  they  are  likely  to  dam,  pro- 
ducing a  lake,  they  have  sometimes  been  supposed  to  be  prehistoric,  built 
by  the  inevitable  Indians. 

It  is  important  to  note  the  action  of  the  sea  waves  upon  projecting 
capes.  As  the  waves  strike  a  point  of  land  they  are  divided,  and  the  water 
is  forced  obliquely  or  laterally  along  the  coast  toward  reentrant  parts. 
Loose  df^bris  is  at  the  same  time  driven  obliquely  away  from  the  projecting 
capes  and  collects  in  the  bays  as  beaches  or  as  sea  walls.  So,  also,  the 
waves  are  constantly  changing  their  direction  under  the  action  of  varying 
winds,  and  beach  matter  is  transported  laterally  along  the  coast  whenever 


44  GLACIAL  GRAVELS  OF  MAINE, 

the  waves  strike  the  shore  obhquely.  As  the  resuh  of  all  these  causes, 
together  with  the  tidal  currents,  the  projecting  parts  of  the  land  are  denuded 
of  loose  matter,  while  the  bays  and  coves  are  strewn  with  beach  gravels. 

Such  are  some  of  the  most  common  modes  of  wave  action  as  exhibited 
along  the  present  beach.  Rising  above  the  beach  cliffs,  we  find  that  a  con- 
siderable part  of  the  island  of  Monhegan  is  bare  of  soil.  The  local  rocks 
weather  very  unequally.  Many  of  the  bare  ledges  of  coarse-grained 
syenitic  granite  have  already  been  shattered  into  bowlders  and  cliff  debris. 
Wherever  the  rock  weathers  slowly  the  rounded  forms  of  the  roches 
moutonn^es  are  beautifully  exhibited.  Everywhere  a  thin  layer  on  the 
surface  has  weathered  away,  and  I  could  find  no  glacial  scratches  on  rock 
long  laid  bare.  On  the  north  shore  was  a  place  where  the  surf  had  recently 
undermined  and  removed  the  till.  Here  the  scratches  were  well  preserved 
and  the  rock  bore  every  appearance  of  having  been  as  violently  glaciated 
as  it  was  anywhere  on  the  mainland.  It  thus  appears  that  the  rounded 
bosses  of  rock  which  cover  a  large  part  of  the  island  are  true  roches 
moutonn^es  and  owe  their  shapes  to  glacial  action.  As  the  ice-sheet  passed 
over  the  island,  it  ought  to  have  left  as  large  a  proportion  of  the  surface 
covered  with  till  as  it  did  elsewhere  on  that  coast.  But  the  proportion  of 
bare  rock  is  unusually  great  on  this  island.  If  we  assume  that  the  whole 
surface  was  originally  covered  with  till,  we  find  that  the  greatest  amount  of 
work  that  can  be  assigned  to  wave  action  at  levels  above  the  present  beach 
cliffs  consists  of  (1)  the  erosion  of  a  considerable  part  of  the  till,  and  (2) 
some  attrition,  which  may  have  erased  the  glacial  scratches  but  did  not 
obliterate  the  characteristic  forms  of  the  roches  moutonne'es.  When  we 
compare  the  ragged  and  uneven  cliff  of  erosion  at  the  present  beach  with 
the  still  moutonn^ed  ledges  at  higher  levels,  it  becomes  evident  that  the  sea 
has  stood  at  or  near  its  present  position  many  times  as  long  as  at  any  higher 
level.  At  the  higher  elevations  the  surf  had  time  to  erode  the  till  from  the 
more  exposed  shores,  but  it  had  not  time  to  form  a  cliff  of  erosion  in  the 
solid  rock  before  a  change  of  level  transferred  the  wave  action  to  higher  or 
lower  rock.  In  other  words,  the  changes  of  level  of  the  sea  were  relatively 
rapid. 

In  a  few  j)laces  imdisturbed  till  was  observed  resting  on  the  glaciated 
rock,  but  over  most  of  those  parts  of  the  island  covered  by  soil  the  super- 
ficial deposits  consisted  of  a  formation  needing  careful  study  in  order  to 


BEACH  AND  COVE  GEAVELS. 


45 


inake  clear  its  origin.  At  first  it  appeared  to  be  till,  but  it  was  soon  seen 
to  liave  lost  the  finest  matter  of  the  till.  All  material  except  the  finest 
remained  in  a  rather  obscurely  stratified  condition.  On  the  northern  slopes 
of  the  island  the  stones  have  been  changed  but  very  little  from  their  till 
shapes;  but  on  the  side  next  the  open  ocean  the  stones  are  much  more 
rounded  and  polished,  though  seldom  showing  such  very  round  shapes  as 
those  of  the  stones  of  the  present  beach.  A  section  from  east  to  west  across 
one  of  the  north-and-south  valleys  of  the  island  is  shown  in  the  accompany- 
ing diagram. 

The  slopes  are  somewhat  exaggerated  in  the  diagi'am.  The  bare 
ledges  on  the  tops  of  the  hills  have  become  weathered  into  bowlders  of 
decomposition.  Some  of  these  are  in  place;  others  have  tumbled  or  slid  a 
short  distance  down  the  slopes,  as  is  proved  by  their  identity  in  composition 
with  the  rocks  that  compose 
the  ledges.  Are  these  bowl- 
ders the  result  of  a  former 
marine  erosion!  The  lower 
part  of  the  valley  is  shown 
in  fig.  6  to  be  filled  by  a 
mass  which  we  now  recog- 
nize as  beach  gravel,  com- 
posed of  the  till  and  any 
rock  which  may  have  been  eroded  or  washed  up  by  the  surf  This  is 
overlain  by  a  thin  soil  composed  of  peat  and  vegetable  mold,  rain  wash, 
weathered  di-ift,  etc.  An  examination  of  the  till  and  the  beach  gravels  at 
high  levels  showed  that  both  are  composed  almost  wholly  of  rocks  found 
on  the  mainland  to  the  north  of  the  island.  I  did  not  succeed  in  find- 
ing a  single  fragment  of  the  same  kind  of  rock  as  that  on  the  island.  The 
beach  gravel  is  evidently  the  residue  left  after  the  erosion  of  the  far-traveled 
till  brought  hither  from  the  north  by  the  ice.  The  finest  matter  of  the  till 
was  washed  out  to  sea  and  lost,  but  the  coarser  matter  remains,  and  con- 
sists of  sand  and  gravel  mixed  with  larger  stones  and  bowlders,  all  more 
or  less  polished  and  rounded  by  water.  The  rarity,  perhaps  total  absence, 
of  local  rock  in  this  ancient  beach  is  a  proof  that  the  sea  did  not  form 
cliffs  of  beach  erosion  in  the  solid  rock,  though  it  was  able  to  remove  large 
.areas  of  till.     It  also  justifies  the  inference  that,  at  least  in  all  the  cases 


Fig.  6. — Trau8ver.se  section  of  aDCient  cove  gravels 


46 


GLACIAL  GRAVELS  OF  MAINE, 


examined,  the  bowlders  of  local  rock  found  lying  upon  the  beach  gravel 
and  the  soil  are  due  to  recent  weathering  and  sliding  of  the  rock,  and  not 
to  wave  erosion. 

Fig.  6  is  drawn  across  the  valley.  Lengthwise  of  the  valley  the  sur- 
face of  the  beach  gravel  has  about  the  same  slope  as  the  solid  rock  of  the 
island.  In  some  cases  one  of  these  plains  of  cove  gravel  can  be  followed 
all  the  way  up  a  valley  to  the  top  of  the  island  and  then  downward  to  the 
sea  on  the  other  side.  The  structure  lengthwise  of  the  valleys  is  shown  in 
the  diagram,  fig.  7. 

If  the  summit  is  narrow  and  rooflike,  the  gravel  is  scanty  or  absent  at 
that  point;  but  where  the  top  is  a  rounded  plateau  the  beach  gravel  is 
continuous  across  the  whole  island.  The  mode  of  formation  of  these  con- 
tinuous sheets  of  gravel,  filling  the  valleys  and  extending  across  the  whole 
island,  is  evident.     As  the  sea  rose  or  fell,  a  valley  would  always  be 


Fig,  7. — Ancient  beaches  sloping  np  from  shore. 


occupied  by  a  bay  or  cove,  and  a  hill  would  form  a  cape.  The  till  would 
be  washed  away  from  the  hills  (then  capes)  and  would  be  drifted  obliquely 
into  the  present  valleys  (then  bays).  If  the  changes  in  level  went  on  at  a 
uniform  and  rather  rapid  rate,  a  continuous  sheet  of  beach  gravel  would  be 
formed  across  the  bottom  of  the  valley  from  the  top  of  the  slope  down  to 
the  present  sea  level.  If  there  were  pauses  in  the  process  of  change  of 
level,  then  terraces  or  cliff's  of  erosion  would  interrupt  the  even  slopes  of 
the  beach.  I  saw  no  trace  of  any  such  pause,  unless  at  about  25  feet 
above  the  present  beach,  where  there  is  an  obscure  terrace.  The  valleys 
which  have  been  covered  in  this  way  by  beach  gravels  are  not,  on  the 
island  of  Monhegau,  more  than  one-fourth  or  one-third  of  a  mile  in  extreme 
breadth.  It  is  evident  that  the  most  violent  waves  must  come  from  the 
side  toward  the  open  ocean,  and  the  fact  that  this  sort  of  gravel  is  more 
rounded  on  the  south  and  southeastern  slopes  of  the  island  is  a  proof  that 
the  stones  owe  their  final  shapes  to  beach  action. 


BEAGil  AND  GOVE  GRAVELS.  47 

That  most  of  tlie  beach  gravel  laid  down  by  the  sea  should  thus  be 
coucentrated  in  the  valleys  in  the  form  of  long  and  rather  narrow  sheets, 
directed  at  nearly  right  angles  to  the  shore,  was  rather  contrary  to  my 
expectations,  and  was  worked  out  only  after  careful  study.  There  is  here, 
on  this  uneven,  rock-bound  coast,  nothing  like  the  long  horizontal  terraces 
iind  ridges  of  beach  gravel  observed  by  Grilbert  in  the  basin  of  the  ancient 
Lake  Bonneville  in  Utah,  or  by  Russell  along  the  old  shore  of  Lake 
Lahontan  in  Nevada,  or  by  Uphani  along  Lake  Agassiz^nothing-  like  the 
"Parallel  Roads  of  Grlen  Roy"  in  Scotland  or  the  old  beaches  of  Lake 
Ontario  and  of  the  other  Great  Lakes. 

In  several  places  on  this  island  beach  gravels  are  to  be  found  abun- 
dantly on  the  north  and  northwest  sides  of  small  conical  hills.  These 
gravels  are  iii  part  due  to  wave  action  from  the  northward,  but  there  is  no 
reason  why  waves  from  that  direction  should  form  beaches  any  deeper  in 
such  places  than  elsewhere  on  the  northern  slopes.  A  large  part  of  this 
gravel  was  washed  around  and  over  the  hill  by  the  larger  waves  from  the 
open  sea  toward  the  south.  In  other  words,  this  gravel  formed  in  lee  of 
the  peak  which  was  then  a  shoal  of  rock  or  small  island.  Instances  are  also 
found  in  Monhegan  where  beach  gravel  was  washed  over  the  top  of  an  east- 
and-west  ridge  and  left  in  the  northern  slopes,  but  this  form  of  beach  is 
better  shown  elsewhere  Here  the  question  is  complicated  by  the  fact  that 
there  was  considerable  wave  action  from  the  north  and  northwest. 

Matinicus  and  Ragged  islands  are  situated  a  few  miles  off  the  coast 
near  the  entrance  of  Penobscot  Bay.  They  are  very  near  each  other  and 
show  nearly  the  same  rocks.  The  eastern  ends  of  both  islands  are  nearly 
bare  of  drift  of  any  kind,  and  are  covered  with  granite  knobs  and  bosses, 
well  moutonnded.  The  rocks  of  the  western  ends  of  the  islands  are  schists, 
and  show  much  more  drift.  The  central  part  of  Matinicus  Island  rises 
about  80  feet  above  the  sea,  and  is  covered  with  a  broad,  gently  sloping', 
lenticular  sheet  of  blue,  compact  till,  10  to  30  or  more  feet  in  depth.  A 
large  part  of  the  till-covered  area  is  strewn  with  several  feet  of  beach 
gravel,  little  rounded  or  worn.  The  till  and  beach  gravel  are  well  exposed 
at  the  present  beach  where  there  are  cliffs  of  erosion  in  the  till.  Evidently 
the  sea  was  able  to  erode  only  a  few  feet  on  the  surface  of  the  till  while  at 
higher  level  than  now,  and  the  slopes  of  the  island  were  so  gentle  that  the 
ei'oded  till  was  left  as  a  broad  sheet,  there  being'  no  valleys  in  which  it 


48  GLACIAL  GRAVELS  OF  MAINE. 

■could  be  concentrated  into  beaches  at  right  angles  to  the  shore.  The  rains 
easily  penetrate  the  beach  gravel,  until  they  reach  the  more  impervious 
till;  they  then  seep  along  the  top  of  the  till  in  the  gravel,  and  escape  as 
small  springs  at  the  beach  cliffs.  The  till  is  compact  and  clayey,  and  con- 
tains great  numbers  of  scratched  stones.  It  appears  to  differ  in  no  imjDor- 
tant  respect  from  the  till  found  in  the  mainland  north  of  this  island. 
Ragged  Island  is  more  diversified  by  hills,  and  the  till  has  been  denuded 
from  the  southern  slopes  of  the  hills  and  di'ifted  into  the  valleys,  forming 
one  or  more  plains  of  beach  gravel  extending  across  the  island  from  south 
to  north,  as  at  Monhegan. 

Isle  au  Haut  is  about  7  miles  long  from  northeast  to  southwest,  and 
about  2  miles  broad.  Its  eastern  and  southern  sides  are  exposed  to  the 
•open  ocean.  On  account  of  the  number  of  fallen  trees  and  the  density  of 
"the  scrub  forest,  the  island  is  difficult  to  explore  and  it  is  impossible  to  get 
any  general  view  of  the  old  beaches.  Near  the  southwestern  extremity  of 
the  island  I  traced  a  line  of  beach  gravel  up  a  valley  to  a  height  of  225 
feet  by  aneroid.  Here  the  rolled  gravel  suddenly  disappeared,  and  above 
that  elevation  only  ordinary  till  could  be  found.  Guided  by  the  barom- 
eter, I  then  went  nearly  around  the  island  at  this  elevation,  and  at  every 
valley  found  rotmded  gravel  and  bowlders  up  to  225  feet,  at  which  eleva- 
tion the  rolled  gravel  began  to  thin  out,  and  the  contour  of  250  feet  was 
plainly  above  the  water-washed  drift.  From  that  elevation  to  the  top  of 
the  highest  hill  (550  feet)  not  one  water-washed  stone  could  I  find,  though 
they  were  very  abundant  and  easily  found  below.  On  the  projecting  angles 
of  the  hills  (which  would  be  capes  with  the  sea  standing  at  high  levels) 
the  till  was  extensively  denuded.  No  cliffs  of  erosion  were  observed  above 
the  present  beach. 

Similar  observations  were  made  near  Southwest  Harbor  and  at  many 
other  points  on  Mount  Desert  Island,  also  at  many  favorable  places  on  the 
mainland.  One  of  the  most  accessible  places  for  examining  the  highest 
beach  is  about  3  miles  northwest  of  Rockland,  in  the  valley  of  Chicka- 
waukie  Stream  and  Lake.  This  valley  is  bordered  on  the  west  by  a  high 
hill  or  ridge,  rising  400  feet  or  more  above  the  sea.  For  several  miles 
along  the  southern  and  eastern  base  of  this  hill  rolled  gravels  are  abun- 
dant.    In  places  the  gravel  takes  the  form  of  a  distinct  terrace  on  the 


BEACH  AFD  COVE  GRAVELS.  49 

hillside,  and  for  30  to  50  feet  above  the  terrace  the  rock  is  nearly  bare  of  till. 
This  terrace  is  very  distinct  along  the  west  side  of  Chickawaukie  Lake, 
where  it  has  been  excavated  for  road  gravel.  The  stones  are  distinctly  worn 
on  the  angles,  but  not  so  much  so  as  in  ordinary  glacial  gravel.  This  beach 
extends  northward  to  the  village  of  Rockville  and  then  bends  eastward  and 
southward  along  the  east  side  of  the  valley.  When  the  sea  stood  at  this 
elevation,  the  Chickawaukie  Valley  would  be  a  bay  nearly  one-half  mile 
wide,  and  since  there  would  be  few  if  any  islands  to  the  south,  it  would  be 
well  exposed  to  the  waves.  Three  times  in  as  many  difiPerent  years  I  have 
visited  the  place  in  order  to  measure  by  aneroid  the  height  of  this  beach, 
and  each  time  I  have  been  prevented  by  local  storms  from  making  accurate 
measurement. 

Another  excellent  locality  for  measuring  the  height  of  the  highest 
beach  is  on  the  southern  slope  of  a  rather  high  range  of  hills  situated  about 
3  miles  north  and  northeast  of  Machias  Village.  The  face  of  the  hill  is 
such  that,  when  the  sea  stood  at  high  level,  there  would  be  hardly  any 
coves  or  bays,  and  it  trends  nearly  east  and  west.  The  country  to  the 
south  is  low,  so  that  it  would  all  be  submerged  and  this  hill  would  be 
exposed  to  the  unbroken  surf  One  can  take  aneroid  readings  and  be  down 
to  the  level  of  tide  water  in  a  few  minutes.  At  220  feet  the  top  of  a  terrace 
of  rolled  gravel  and  cobbles  was  observed.  The  stones  were  distinctly 
polished  and  somewhat  rounded  at  the  angles.  This  terrace  is  from  10 
to  30  feet  wide,  and  is  a  prominent  feature  of  the  hillside.  The  gravel 
becomes  thinner  above  the  terrace,  a  sort  of  sheet  overlying  the  till. 
Rolled  stones  could  be  found  here  and  there  at  240  feet.  At  250  feet  only 
ordinary  till  stones  could  be  found,  and  from  this  point  upward  the  hillside 
was  searched  for  almost  a  mile,  only  till  being  found.  The  contrast  in 
shape  between  the  stones  of  the  till  and  those  of  the  beach  gravel  was  so 
great  that  there  was  no  difficulty  whatever  in  distinguishing  them.  The 
sea  did  not  here  lay  the  rock  bare,  or  at  least  did  not  leave  it  bare.  The 
average  of  these  and  many  similar  measurements,  with  a  good  aneroid, 
give  the  height  of  the  highest  beach  near  the  outer  coast  line  as  about  225 
feet  for  the  region  east  of  Penobscot  Bay,  and  230  feet  for  the  region 
between  that  bay  and  the  Kennebec  River.  West  of  the  Kennebec  I  have 
not  yet  been  able  to  measure  the  height  of  the  highest  beach.     A  good 

MON  XXXIV 4 


50  GLACIAL  GEAVELS  OF  MAINE. 

place  for  doing  so  is  on  Black  Strap  Mountain,  in  the  western  part  of  North 
Falmouth.  It  is  desirable  that  the  elevation  of  these  old  beaches  should  be 
measured  by  the  spirit  level. 

It  should  be  noted  that  in  this  report  I  am  describing  only  what  I 
have  seen.  The  sea  beach  reported  by  Professor  Hitchcock  at  Fort  Kent 
(Geological  Report,  1862)  I  have  not  had  opportunity  to  examine.  In  this 
connection  it  should  be  added  that  Mr.  R.  Chalmers,  of  the  Canadian 
Geological  Survey,  has  determined  the  height  of  the  highest  beach  in 
western  New  Brunswick  to  be  about  220  feet,  and  it  becomes  somewhat 
lower  toward  Nova  Scotia.  Since  the  height  of  the  sea  rapidly  diminishes 
southward  in  New  Hampshire  and  Massachusetts,  it  appears  that  the  aver- 
age elevation  of  the  sea  on  the  Atlantic  Coast  south  of  Nova  Scotia  was 
greatest  in  the  region  lying  between  Portland  and  the  Penobscot  Bay,  or 
perhaps  near  the  mouth  of  the  Narraguagus  River. 

To  summarize:  The  rolled  gravel  of  the  old  beaches  is  so  different 
from  the  till  in  composition  and  shape  of  the  stones,  the  raised  beaches  are 
so  plainly  to  be  recognized  on  all  the  exposed  coasts  of  Maine  up  to  the 
elevations  above  stated  and  then  so  suddenly  disappear,  that  I  feel  justified 
in  referring  to  the  contour  of  about  230  feet  as  the  highest  elevation  of  the 
sea  on  the  coast  of  Maine  after  the  melting  of  the  ice-sheet  over  the  coast 
region.  As  to  what  may  have  happened  in  strictly  glacial  time,  when  the 
ice  covered  the  land  and  extended  far  out  to  sea,  and  when  the  sea  may 
have  stood  at  far  higher  levels  but  was  perhaps  prevented  by  the  deep  sheet 
of  ice  from  having  access  to  the  land  and  forming  gravel  beaches,  unless 
possibly  here  and  there  at  long  intervals  in  the  most  exposed  situations  on 
the  higher  hills  and  mountains — concerning  these  possibilities  it  must  be 
admitted  that  my  observations,  while  not  inconsistent  with  them,  do  not 
afford  the  necessary  proof  Elsewhere  are  recorded  facts  showing  that 
probably  the  sea  was  at  a  higher  level  50  miles  back  from  the  coast  than 
on  the  coast  itself,  i.  e.,  the  relative  level  of  the  interior  and  coast  regions 
may  not  have  been  the  same  then  as  now,  there  being  a  greater  submer- 
gence toward  the  northwest. 

The  foregoing  remarks  relate  chiefly  to  beaches  having  a  southern 
exposure.  In  many  places  where  the  waves  swept  over  the  tops  of  hills 
the  till  was  denuded  from  the  top  of  the  hill  and  left  as  a  beach  terrace  just 
north  of  the  crest.     The  waves  from  the  side  of  the  open  ocean  had  so 


BEACH  AND  COVE  GRAVELS. 


51 


much  more  power  than  those  from  the  coast  side  that  much  more  beach 
matter  was  swept  northward  from  hilltops  than  southward. 

A  good  instance  of  this  kind  of  beach  is  found  a  few  miles  south  of 
Machias,  at  the  terminal  moraine  which  extends  from  a  branch  of  English- 
mans  River  northeastward  to  near  the  head  of  Little  Kennebec  Bay.  On 
the  seaward  side  of  the  morahial  ridge  the  surface  is  strewn  with  bowlders 
and  laro-e  stones.  If  they  were  once  water  polished,  the  poHshed  surface 
has  weathered  away.  On  the  northern  slope  is  a  deposit  of  stratified  sand 
and  gravel  several  feet  deep,  with  a  few  larger  stones,  as  shown  in  the 
accompanying  cross  section.  The  axis  of  the  ridge  is  composed  of  till. 
Evidently,  the  waves  denuded  the  upper  portion  of  the  till  on  the  southern 
slope  and  washed  the  finer  matter  over  the  top  of  the  ridge. 

An  unusually  fine  exhibit  of  the  same  sort  of  beach  is  found  on  the 
northwestern  slope  of  a  northeast-and-southwest  hill  situated  IJ  miles  east 
of  Boothbay  Harbor.  More  or  less  beach  matter  is  found  all  along  the 
northern  crest  of  the  ridge. 
In  addition  there  are  several 
large  bars  of  beach  gravel 
which  extend  northward,  ob- 
liquely down  the  hill,  for 
about  one-eighth  of  a  mile. 
These  ridges  are  situated  directly  north  of  low  places  in  the  ridge.  Here, 
evidently,  the  higher  parts  of  the  hill  were  at  one  time  islands,  separated  by 
narrow  straits  which  occupied  what  are  now  the  lowest  parts  of  the  ridge. 
The  waves  converged  the  beach  matter  and  washed  it  through  the  narrow 
straits — now  represented  by  the  low  cols — and  a  ridge  was  formed  opposite 
each  strait.  Another  fine  locality  is  on  the  south  side  of  the  high  hill  which 
borders  the  Chickawaukie  Valley  on  the  west,  about  1^  miles  west  from 
Rockland.  Here  a  large  amount  of  beach  gravel  gathered  on  tlie  north 
side  of  a  conical  hill  which  lay  a  short  distance  south  of  the  main  hill.  The 
place  is  situated  just  west  of  the  lime  quarries. 

In  some  of  the  most  exposed  situations  the  beach  gravels  extend  con- 
tinuously from  the  highest  beach  down  to  present  sea  level,  but  such  places 
form  the  exception.  As  we  pass  inside  of  the  outer  islands  the  power  of  the 
waves  rapidly  decreases.  Everyone  who  has  sailed  along  the  coast  knows 
how  much  less  violent  are  the  waves  in  lee  of  even  a  small  island.     This 


Fig  8.— Section  aLm^'!  teimuial 


52  GLACIAL  GRAVELS  OF  MAINE, 

accounts  in  part  for  the  absence  of  such  long  and  continuous  beach  terraces 
as  those  of  lakes  Bonneville,  Lahontan,  and  Agassiz.  We  have  seen  that 
changes  in  the  level  of  the  sea  were  rapid,  so  that  the  sui-f  beat  for  only  a 
relatively  short  time  at  any  one  level;  but  we  must  also  remember  that  the 
land  surface  of  most  of  the  coast  region  of  Maine  is  very  uneven,  consisting 
largely  of  hills  and  valleys.  The  hills  are  in  general  not  high,  but  high 
enough  to  form  a  multitude  of  islands  oif  the  shore  as  the  sea  changed  its 
level  Avith  respect  to  the  land.  As  the  sea  rose  and  fell,  not  only  did  the 
shore  outline  change  greatly,  but  the  number  and  positions  of  the  islands 
changed  also.  Each  island  more  or  less  protected  a  portion  of  the  main- 
land from  the  fury  of  the  Atlantic  waves.  Although  the  waves  must  have 
beat  against  all  that  jDart  of  Maine  situated  below  230  feet,  long  horizontal 
beaches  could  not  be  formed,  partly  because  of  the  converging  of  the  beach 
outline  into  the  bays,  and  partly  because  of  the  great  numbers  of  protecting 
islands.  The  places  were  comparatively  few  which  were  so  exposed  that 
large  beaches,  measured  either  hoi'izontally  or  at  right  angles  to  the  shore, 
were  deposited.  The  small  beaches  which  must  have  been  formed  at  that 
time  in  the  landlocked  bays  and  fiords  are  recognizable  now  either  not  at 
all  or  only  with  difficulty.  Probably  the  rarity  of  long,  continuous  beaches 
is  also  due  in  part  to  shore  ice.  Even  now,  except  on  the  most  exposed 
coasts,  the  shore  ice  affords  considerable  protection  against  the  winter 
storms.  It  is  a  fair  inference  that  at  the  time  the  walrus  came  as  far  south 
as  Portland  the  shore  ice  was  more  abundant  than  at  present  and  somewhat 
resembled  the  Arctic  ice  foot. 

Resume. — For  scveral  reasons  no  long  and  continuous  horizontal  beaches 
were  formed  on  the  coast  of  Maine  by  the  sea  in  late  glacial  and  postglacial 
time  while  it  stood  above  its  present  level: 

1.  The  changes  of  level  were  too  rapid  to  permit  the  formation  of  cliffs 
of  erosion  in  the  solid  rock. 

2.  Dui'ing  the  comparatively  brief  time  the  surf  beat  upon  any  one 
portion  of  the  land  the  enei'gy  of  the  waves  was  chiefly  expended  in  erod- 
ing the  till  and  drifting  it  away  from  the  capes  into  the  bays. 

3.  The  positions  of  the  exposed  bays  and  headlands  constantly  shifted 
during  the  changes  in  level  of  the  sea,  partly  on  account  of  the  changes  in 
the  shore  line  and  partly  because  of  the  appearance  or  disappearance  of 
protecting  islands  off  the  shore. 


FOSSILS  IN  THE  RAISED  BEACHES.  53 

4.  The  beach  was  more  or  less  protected  by  shore  ice. 

5.  The  surf  probablj^  beat  against  the  ice  during  all  the  time  of  its 
advance  and  until  the  ice  had  retreated  north  to  the  central  part  of  Maine. 

The  net  result  of  these  causes  was  that  recognizable  beaches  are  found 
only  at  intervals.  Most  of  that  portion  of  Maine  below  230  feet  affords 
either  no  beach  gravel  or  only  scant  quantities  of  it. 

It  follows  from  the  above  that  the  finding  of  a  sea  wall  across  a  valley 
at  a  certain  elevation,  or  of  a  beach  terrace  on  a  hillside,  Avould  not  neces- 
sarily indicate  a  long  pause  of  the  sea  at  that  level  unless  the  relief  forms 
of  the  adjacent  land  show  that  the  sea  waves  would  have  as  easy  access  at 
other  levels  as  at  that.  The  fact  that  those  valleys  of  most  uniform  slope 
and  exposure  to  the  sea  do  not  show  well-defined  beach  terraces  proves  that 
at  least  the  fall  of  the  sea  proceeded  at  a  nearly  uniform  rate,  unless  the 
pauses  at  225  to  230  feet  and  at  20  feet  be  exceptions. 

FOSSILS    IN    THE    RAISED    BEACHES. 

On  the  western  slopes  of  Munjoy  Hill,  Portland,  as  pointed  out  to  me 
by  Mr.  C.  B.  Fuller,  the  impressions  of  various  shells  and  the  burrows  of 
divers  mollusks,  etc.,  are  traceable  in  sedimentary  sand  and  fine  gravel  at 
elevations  of  50  or  more  feet  above  the  sea.  The  top  of  the  hill  is  covered 
with  a  sheet  of  glacial  gravel,  and  the  fossils  are  in  beds  which  are  stratified 
parallel  with  the  slopes  of  the  hill.  The  hills  of  Portland  would  not  l^e 
in  the  most  exposed  situation  when  the  sea  beat  upon  their  upper  portions, 
yet  there  would  be  enough  of  a  surf  to  erode  considerable  of  the  glacial 
sand  and  gravel  from  the  top  of  Munjoy  Hill.  On  the  whole,  I  consider  it 
more  probable  that  the  glacial  sand  and  gravel  containing  fossils  is  not  in 
the  condition  it  was  in  when  deposited  by  the  glacial  streams — that  it  was 
changed  to  beach  matter  by  the  waves  of  the  sea,  which  washed  it  from  the 
top  of  the  hill  and  deposited  it  on  the  lower  slopes.  On  the  modern  gravel 
beaches  most,  if  not  all,  of  the  shells  are  being  pulverized  so  rapidly  by 
the  beating  of  the  surf  that  it  is  doubtful  if  many  of  them  sur-^-ive  long 
enough  to  become  embedded  in  the  beach  matter,  unless  it  be  below  low  tide. 
In  several  parts  of  the  State  I  have  examined  excavations  in  the  high 
beaches  at  200  feet  and  found  no  shells  and  no  impressions  or  casts  of  fos- 
sils large  enough  to  be  recognized  by  the  unassisted  eye,  and  no  burrows. 


54  GLACIAL  GRAVELS  OF  MAI^s^E. 

At  lower  levels  there  are  some  fossils  iu  the  raised  sand  beaches,  but  I  have 
found  none  in  the  coarse  gravel  and  shingle  beaches. 

SANDS  AND  CLAYS. 

Although  the  areas  of  denuded  rock  near  the  coast  suggest  that  the 
quantity  of  raised  beach  gravel  must  be  large,  yet  it  is  small  when  com- 
pared with  the  broad  sheets  of  sand  and  clay  deposited  along  the  coast 
Avhile  the  sea  stood  at  higher  levels  than  now.  Only  a  small  portion  of 
these  finer  sediments  can  have  been  derived  from  the  till  and  rock  which 
were  washed  away  and  assorted  by  the  ocean.  There  was  not  much  wave 
erosion,  except  on  the  most  exposed  coast,  and  this  was  situated  so  far  south 
tliat  the  eroded  till  must  have  been  carried  out  to  sea  and  can  not  have  con- 
tributed much  to  the  marine  clays  as  we  find  them.  The  marine  clays 
now  exposed  on  the  land  are  composed  chiefly  of  the  finer  sediments  poured 
into  the  sea  by  glacial  streams  or  by  swollen  rivers.  Practically  they  are 
marine  deltas. 

The  facts  as  to  the  fossils  of  the  marine  beds  are  so  well  known  that 
only  the  briefest  reference  need  be  made  to  them.  All  writers  on  the  sub- 
ject agree  that  about  the  time  of  the  melting  of  the  latest  great  ice-sheet  of 
this  region  the  sea  stood  considerably  above  its  present  level,  varying  from 
a  few  feet  on  Long  Island  Sound  to  500  feet  at  Montreal.  The  sediments 
deposited  in  the  sea  after  the  ice  retreated  from  the  St.  Lawrence  basin  are 
well  represented  along  Lake  Champlain,  and  were  there  studied  at  an  early 
date;  hence  the  corresponding-  deposits  of  this  epoch  have  been  termed 
Champlain  by  Hitchcock,  Dana,  and  others.  A  few  years  ago  a  nearly 
complete  skeleton  of  a  walrus  was  found  in  marine  beds  at  Portland,  and 
is  now  preserved  in  the  collections  of  the  Natural  History  Society  of  that 
place.  Bones  of  whales,  seals,  and  moUuscan  life  characteristic  of  an  icy 
sea  have  been  found  in  these  beds  in  great  numbers,  as  was  early  reported 
by  Jackson,  Hitchcock,  Dawson,  and  others.  In  addition  to  the  marine 
fossils,  it  is  claimed  that  certain  teeth,  now  in  the  Allen  Collection  at  Bruns- 
wick, were  found  in  the  marine  clay  at  Gardiner.  These  teeth  were  pro- 
nounced by  several  authorities  to  be  those  of  the  bison,  and  on  this  account 
Professor  Packard,  in  his  "Glacial  Phenomena  of  Labrador  and  Maine,"^ 
held  that  the  higher  lands  were  inhabited  by  the  bison  at  the  time  the 

'  Memoirs  of  the  Boston  Society  of  Natural  History,  vol.  1,  pp.  210-262,  Boston,  1866-1869. 


LOWER  OLAYS.  55 

marine  clays  were  being  deposited;  and  if  so,  there  must  have  Ijeen  abun- 
dant land  vegetation.  These  teeth  have  since,  however,  been  submitted  by 
Prof.  L.  A.  Lee,  of  Bowdoin  College,  to  Mr.  J.  A.  Allen,  author  of  "The 
American  Bisons,  living  and  extinct."^  This  expert,  after  comparing  them 
with  a  large  number  of  bison  teeth,  pronounced  them  to  be  probably  cow's 
teeth,  and  of  very  modern  date  of  deposition.  In  the  present  state  of  the 
argument  it  will  not  do  to  insist  on  the  ancient  date  of  these  teeth,  and  the 
inference  of  a  land  vegetation  in  Maine  at  the  time  of  the  dej^osition  of 
marine  clays  can  hardly  be  considered  sustained. 

The  Canadian  geologists  very  generally  employ  the  terms  Leda  Clay 
and  Saxicava  Sand  for  the  lower  and  upper  marine  beds,  respectively.  The 
lower  clays  of  Maine  contain  Leda  and  other  fossils  indicative  of  a  muddy 
bottom,  and  occasionally  in  a  sandy  beach  I  have  found  Saxicava  and  other 
fossils  characteristic  of  that  sort  of  sea  bottom.  We  have  seen  that  the 
high  beaches  are  not  found  continuously,  but  only  here  and  there  in  favor- 
able situations.  Over  almost  all  the  area  of  the  marine  beds  of  Maine  the 
lower  clay  (Leda  Clay?)  is  not  overlain  by  a  fossiliferous  sand.  With 
respect  to  Maine  it  is  doubtful  if  the  terms  Leda  Clay  and  Saxicava  Sand 
can  be  used  in  a  stratigraphic  sense  as  applying  to  deposits  of  different  age 
laid  down  one  above  the  other;  but  the  terms  may  well  be  used  to  indicate 
the  nature  of  the  sediments  which  were  deposited  at  different  depths  and 
tinder  different  shore  conditions.  On  such  an  irregular  coast  as  that  of 
Maine  the  shore  conditions  would  often  vary  rapidly.  My  investigations 
do  not  as  yet  enable  me  to  give  the  chronology  of  the  shallow-water  sands 
and  the  offshore  clays.  As  it  is  not  my  purpose  to  refer  to  the  marine 
beds  except  as  they  are  related  to  the  glacial  sediments,  it  is  not  necessary 
here  to  give  particular  descriptions  of  the  fossils. 

THE   LOWER   CLAYS:    DELTAS   DEPOSITED   BY   aLACIAL    STREAMS. 

As  already  stated,  the  lower  clays  are  often  richly  fossiliferous,  but 
the  fossils  are  by  no  means  evenly  distributed.  Thus,  both  at  Brunswick 
and  Gardiner  the  lower  clays  contain  great  numbers  of  shells;  while  at 
East  Bowdoinhara,  intermediate  between  those  places,  the  fine  blue  clay 

■Memoirs  of  the  Geological  Survey  of  Kentucky,  vol.  1,  part  2,  and  memoirs  of  the  Museum  of 
Comparative  Zoology  at  Harvard  College,  both  Cambridge,  1876;  also  Ninth  Annual  Report  of  the 
U.  S.  Gool.  and  Geog.  Surv.  Terr.,  pp.  443-587,  Washington,  1877. 


56  GLACIAL  GRAVELS  OF  MAINE. 

wliich  overlies  the  till  contains  very  few  fossils,  and  over  large  areas  none 
at  all  could  be  found.  The  lower  beds  often  vary  in  composition.  Gen- 
erally they  are  a  fine  blue  clay,  but  in  many  places  they  consist  of  a  fine 
sand,  which  is  sometimes  quicksand.  These  alternations  of  fine  sand  and 
clay  are  in  a  great  measure  independent  of  the  relief  forms  of  the  land, 
and  do  not  represent  the  horizontal  gradations  of  sediment  depending  on 
depths  of  Avater.  They  are  rather  such  variations  as  could  be  expected  in 
a  sea  into  which  a  great  number  of  sediment-laden  streams  were  pouring 
and  where  the  fineness  of  the  sediments  was  determined  chiefly  by  the 
positions  of  the  mouths  of  these  streams.  In  the  early  part  of  this  epoch 
the  streams  were  smaller  than  they  were  later,  and  were  mostly  glacial 
streams.  The  positions  of  the  mouths  of  the  streams  were  constantly 
changing  daring  the  retreat  of  the  ice,  and  would  be  aff'ected  also  by 
changes  in  the  level  of  the  sea.  As  elsewhere  noted,  what  appears  to  be  a 
kame  or  osar  border  clay  is  sometimes  richly  fossiliferous.  These  fossils 
were  probably  deposited  in  bays  in  the  ice,  into  which  the  salt  water 
reached,  and  while  most  of  the  ice  was  still  unmelted.  They  therefore 
date  from  an  early  part  of  the  marine-clay  period  in  Maine. 

THE  UPPER  CLAYS  :  DELTAS  DEPOSITED  BY  ORDINARY  RIVERS. 

In  the  upper  layers  of  the  marine  clays  and  clay  loams  I  have  found 
but  few  fossils.  As  noted  elsewhere,  the  same  observations  have  been  made 
by  Professor  Lee  at  Brunswick  and  Professor  Stanley  at  Lewiston.  The 
probability  of  finding  fossils  in  the  upper  clays  is  greatest  near  the  sea  and 
away  from  the  great  river  valle5^s.  The  clays  are  deepest  in  the  larger 
valleys  and  near  where  the  great  glacial  rivers  flowed  into  the  sea.  The 
fact  that  fossils  are  rarest  where  the  clay  is  deepest  proves  unfavorable  con- 
ditions for  marine  life  near  the  mouths  of  both  the  glacial  rivers  and  the 
ordinary  rivers.  In  other  words,  the  vast  influx  of  ice-cold  and  muddy 
fresh  water  during'  the  final  melting  of  the  great  glacier  was  destructive  of 
marine  life. 

The  i-arity  of  fossils  contained  in  the  upper  clays  and  silts  makes  it 
very  difficult  to  determine  where  the  marine  beds  end  and  those  of  estuarine 
and  fresh  water  origin  begin.  For  instance,  a  nearly  continuous  sheet  of 
clay  extends  from  the  sea  up  the  valleys  of  the  Kennebec  and  Sandy  rivers 
to  a  height  of  450  feet  or  more.     Below  230  feet  this  clay  is  usuallj^  dark 


UPPEE  CLAYS.  57 

blue  to  brownish  blue;  above  that  it  is  bluish  gray;  otherwise,  to  the  unas- 
sisted eye,  the  clay  appears  nearly  the  same  throughout  its  whole  extent. 
The  absence  of  marine  fossils  does  not  prove  the  exact  height  of  the  ocean, 
for  this  clay  is  practically  nonfossiliferous  almost  to  the  coast,  200  feet  below 
Avhere  the  sea  has  stood,  according  to  the  evidence  both  of  fossils  and  raised 
beaches.  This  rarely  fossiliferous  sheet  of  clay  is  the  basal  clay  of  the 
river  valleys  above  230  feet  and  the  upper  layer  of  the  marine  clay  below 
that  elevation. 

Above  the  clay  which  forms  the  lower  stratum  of  the  alluvium  of  the 
river  valleys,  we  find  in  the  upper  portions  of  these  valleys,  overlying 
the  basal  clay,  a  stratum  of  coarse  sand,  or  sand  mixed  with  gravel  and 
cobbles.  This  extends  across  the  whole  of  the  valley.  As  we  descend  the 
valley  we  find  at  a  certain  point  that  the  coarse  matter  becomes  finer,  and 
soon  passes  by  horizontal  transitions  into  sand,  which  spreads  far  and  wide 
and  covers  both  the  fossiliferous  and  nonfossiliferous  clays.  In  general,  the 
slope  of  the  valley  above  the  point  of  change  from  coarser  to  finer  sedi- 
ments is  now  not  very  different  from  the  slope  below  that  point.  This 
rather  sudden  transition  of  sediments  can  easily  be  explained  as  due  to 
the  checking  of  the  current  where  the  rivers'  flowed  into  the  sea  of  that 
time.  Tried  by  this  test,  the  sea  may  have  stood  at  400  or  more  feet  above 
present  sea  level  in  both  the  Andi'oscoggin  and  Kennebec  vallej^s.  This 
would  imply  a  greater  elevation  of  the  sea  in  the  upper  parts  of  these  val- 
leys than  is  shown  by  the  beaches  near  their  mouths.  There  is  as  yet  no 
fossiliferous  evidence  of  siich  an  elevation  of  the  sea  in  the  upper  part  of 
these  valleys,  and,  as  suggested  elsewhere,  if  we  enlarge  our  ideas  of  the 
size  of  the  estuaries  and  lower  parts  of  the  rivers  at  that  time,  it  is  possible 
to  interpret  the  facts  as  exhibited  in  the  field  consistently  with  the  elevation 
shown  hj  the  fossils  and  raised  beaches — about  230  feet.  It  is  certain  that 
in  wide  valleys  or  level  plains  the  upper  sands  begin  to  spread  laterally  over 
the  marine  clays  at  not  far  above  230  feet.  In  the  valley  of  the  Andros- 
coggin River  these  upper  sands  are  well  exhibited  as  delta  sands  deposited 
by  the  river  in  the  sea.  They  extend  all  the  way  from  a  short  distance 
above  Lewistoii  to  the  sea  at  Harpswell,  and  send  out  a  bi'anch  southward 
through  Durham  and  Pownal  to  Yarmouth.  In  the  valley  of  the  Kennebec 
the  river  delta  sands  end  on  the  south  not  far  from  AVaterville. 


58  GLACIAL  GEAVELS  OF  MAINE. 


SUMMARY. 


Marine  erosion  of  the  till  and  solid  rock  contributed  Ijtit  a  small  por- 
tion of  the  marine  sands  and  clays  of  Maine.  The  lower  marine  beds  of 
Maine  are  clays  and  very  fine  sands  Avhich  are  prevailingly  fossiliferous. 
The  upper  clays  are  rarely  fossiliferous,  and  appear  to  be  contemporaneous, 
or  nearly  so,  with  the  basal  clay  of  the  valley  diift.  Overlying  the  clay 
of  the  valley  drift  is  a  stratum  of  coarse  matter,  which  changes  to  sand  near 
the  old  shore  line  of  the  sea,  and  then  extends  for  some  distance  seaward 
as  a  fluviatile,  not  a  glacial,  delta.  The  facts  indicate  that  the  lower  clays 
are  chiefly  the  finer  sediments  of  glacial  streams.  The  supply  of  sediment 
was  at  that  time  moderate,  and  marine  life  flourished.  Later  there  was  a 
great  rush  of  glacial  waters,  and  about  the  same  time  the  ordinary  streams 
began  to  flow.  These  conditions  were  unfavorable  to  marine  life.  Still 
later  the  sediments  poured  into  the  sea  were  almost  wholly  those  brought 
by  the  present  rivers,  then  swollen  to  great  size.  The  sands  last  to  be 
deposited  border  the  river  valleys  and  are  plainly  deltas  formed  in  the  sea 
off'  the  mouths  of  the  rivers.  The  earlier  clays  are  more  widely  spread, 
and  cover  the  whole  area  submerged  by  the  sea,  and  their  thickness  bears  a 
relation  to  the  systems  of  glacial  gravel  rather  than  to  the  modern  rivers. 

The  distribution  of  the  marine  beds  is  approximately  shown  in  the 
accompanying  map,  PI.  II. 

VALLEY  DRIFT. 

The  mass  of  unconsolidated  sediments  which  is  found  covering  the 
bottoms  of  most  of  the  New  England  valleys  early  attracted  the  attention 
of  geologists.  Various  names  have  been  given  to  it,  the  most  common 
being  terraces,  valley  terraces,  and  valley  drift  or  alluvium.  All  agree  that 
the  material  was  transported  to  its  present  position  by  water,  though  some- 
times it  has  been  referred  to  marine  rather  than  fluviatile  action.  The 
so-called  "intervals"  of  the  Maine  streams  are  almost  always  plains  of 
aqueous  sediment,  which  are  usually  terraced.  Elsewhere  are  given  brief 
descriptions  of  the  alluvium  of  the  larger  valleys  of  the  State.  A  general 
discussion  of  this  deposit  is  therefore  postponed  to  a  subsequent  page.  At 
present  the  attention  of  the  reader  is  called  to  the  more  important  facts. 

Perhaps  the  most  important  fact  regarding  the  sedimentary  di'ift  of  the 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  II 


VA.LLEY  DEIFT.  59 

valleys  of  Maine  is  that  there  is  a  profound  difference  between  the  sedi- 
ments of  the  valleys  above  and  below  about  230  feet  above  sea  level. 
Below  that  level  the  country  was  beneatli  the  sea,  and  is  covered  with 
clays  and  other  marine  deposits.  Unlike  ordinary  valley  alluvium,  the 
marine  beds  do  not  as  a  whole  show  a  level  plain  in  the  bottoms  of  the  val- 
leys. Over  large  areas  the  surfaces  of  the  clay  plains  undulate  somewhat 
like  the  till  beneath  them,  especially  in  the  broad  valleys  which  were  arms 
of  the  sea,  several  to  20  miles  broad  when  the  sea  stood  at  its  highest 
level.  As  elsewhere  noted,  the  clays  are  thickest  near  the  mouths  of  the 
glacial  rivers.  Hence  when  we  find  marine  deltas  of  glacial  sediments  in 
rather  naiTOw  valleys,  the  offshore  clays  usually  extend  over  the  whole  val- 
ley and  have  a  nearly  horizontal  surface  across  it.  This  closely  simulates 
fluviatile  sediments.  The  present  rivers  beg'an  to  flow  at  the  time  the  sea 
stood  at  its  highest  level.  The  fluviatile  delta  sands  which  these  rivers  at 
that  time  poured  into  the  sea  are  easily  recognizable  and  for  a  few  miles 
extend  entirely  across  their  valleys,  like  fluviatile  drift.  A  little  below  230 
feet  the  sands  no  longer  spread  over  the  whole  space  then  under  water,  but 
form  plains  from  1  to  4  miles  wide  overlying  the  fossiliferous  clays,  and 
follow  not  only  the  main  valley  but  also  sometimes  lateral  valleys  which 
were  then  straits,  such  as  the  line  of  sands  that  extends  from  the  Andros- 
coggin at  Durham  southward  to  Pownal. 

Above  the  level  of  230  feet  we  find  sheets  of  sediments  covering-  the 
bottoms  of  the  valleys,  usually  terraced  like  the  upper  Connecticut  Valley, 
and  in  most  cases  extending  from  one  side  of  the  valley  to  the  other.  In 
this  portion  of  Maine  (which  was  not  in  postglacial  time  beneath  the  sea) 
we  -find  the  valley  drift  comparable  to  that  of  the  rest  of  northern  New 
England.  It  will  therefore  be  understood  that  the  following  remarks  apply 
only  to  that  part  of  the  State  situated  above  about  230  feet. 

Over  the  more  level  regions  the  lowest  layer  of  the  valley  drift  is  usu- 
ally silt  or  clay,  the  upper  layers  consisting  of  coarser  material,  such  as 
sand  or  gravel.  As  we  approach  the  highlands  the  sediments  become 
coarser  in  composition.  Among  the  high  hills  the  slopes  are  often  80  feet 
or  more  per  mile,  and  the  valley  drift  contains  cobbles,  bowlderets,  and 
sometimes  even  bowlders.  In  general,  the  stones  found  in  the  valley  sedi- 
ments of  Maine  are  very  much  less  worn  and  rounded  than  those  in  the 
kames  and  osars.     Some  exceptions  ought  to  be  noted.     Thus,  near  the 


60  GLACIAL  GEAYELS  OF  MAINE. 

nortliern  ends  of  some  of  the  osars  and  in  some  of  the  smaller  hillside 
kames  the  stones  are  but  little  waterworn,  and  the  same  is  true  of  the  stones 
at  the  margins  of  some  of  the  osar-plains  and  of  the  smaller  solid  kame 
plains.  On  the  other  hand,  the  large  stones  of  the  coarse  valley  drift  from 
the  swift  mountain  streams  are  often  quite  well  waterwoi-n,  though  seldom 
as  much  so  as  those  of  the  kames  and  osars.  With  the  exception  of  these 
steep  valleys  among  the  hills,  whenever  in  Maine  we  find  a  plain  of  appar- 
ent valley  drift  composed  of  stones  considerably  rolled  and  rounded,  we  are 
sure  to  find  one  of  the  following  conditions: 

1.  A  shoi't  distance  up  the  valley  the  stream  may  have  eroded  a 
ravine  or  channel  through  a  deep  inass  of  till.  In  this  case  the  stones  are 
those  of  the  eroded  till,  which  were  worn  and  rolled  at  the  rapids  formed 
while  the  stream  was  cutting  through  the  till  barrier.  Such  a  formation 
occurs  at  Kingman  and  at  many  other  places.  The  proof  in  such  cases  is 
not  complete  unless  it  appears  that  the  deposit  of  well-rolled  stones  extends 
only  a  short  distance  below  the  channel  of  erosion,  and  that  beyond  that 
point  the  character  of  the  valley  drift  changes. 

2.  If  we  trace  both  northward  and  southward  such  a  plain  of  much 
worn  stones,  we  may  find  it  leaving  the  valley  and  going  up  and  over  hills 
to  other  drainage  basins,  or  it  may  leave  the  bottom  of  the  valley  and  go 
up  along  a  hillside  as  a  sort  of  terrace.  In  these  cases  the  apparent  j^lain 
of  valley  drift  is  an  osar-plain,  or  broad  osar,  happening  to  occupy  the 
bottom  of  a  valley. 

3.  To  the  north  such  a  plain  of  highly  rounded  stones  may  end  in  a 
kame  or  osar,  while  to  the  south  the  plain  becomes  finer  in  composition, 
passing  from  gravel  to  sand,  and  finally  to  clay.  In  this  case  our  plain  of 
well-rolled  stones  is  a  frontal  plain  of  glacial  sediments,  consisting  of  matter 
that  was  brought  down  by  glacial  streams  to  the  extremity  of  the  ice  (i.  e., 
the  end  of  the  osar),  and  there  was  poured  out  into  the  open  valley.  From 
that  point  southward  the  sediment  is  spread  across  the  bottom  of  the  valley 
like  purely  flu^datile  drift,  yet  the  stones  received  their  shapes  almost 
entirely  while  l^eing  transported  in  the  ice  channels  of  the  glacier,  which  at 
the  time  of  deposition  lay  to  the  north.  Several  such  frontal  or  overwash 
plains  are  described  elsewhere. 

In  addition  to  the  above-named  glacial  or  semiglacial  deposits,  we  also 
find,  in  a  few  valleys  having  a  northward  slope,  sediments  that  were  dropped 


EIVER  TERRACES.  61 

in  local  lakes  which  wei'e  confined  between  the  ice  on  the  north  and  the 
hills  to  the  south  during-  the  final  melting  of  the  great  glacier. 

And  now,  after  eliminating  these  more  distinctly  glacial  sediments,  how 
can  we  account  for  the  remainder  of  the  valley  drift!  A  great  part  of  it 
is  frontal  matter,  derived  from  glaciers  situated  far  to  the  north.  Such 
sediment  would  consist  mostly  of  clay  derived  from  the  muddy  glacial 
streams,  representing-  work  done  beneath  the  ice.  In  such  a  case  the  glacier 
of  that  time  was  so  remote  from  where  we  now  find  the  sediment  that  it  is 
difficult  to  trace  the  connection. 

RIVER    TERRACES. 

Here  and  there,  at  waterfalls  and  in  the  swifter  parts  of  their  courses, 
the  streams  of  Maine  have  eroded  all  the  superficial  drift,  and  may  even 
flow  in  channels  excavated  in  the  solid  rock.  A  few  of  these  rock  channels 
approach  the  dignity  of  canyons,  as  those  of  the  Kennebec  above  the 
Forks  and  of  the  Penobscot  below  Ripogenus  Lake.  In  general,  the 
streams  floAV  in  channels  lying  wholly  or  chiefly  in  the  till  or  other  super- 
ficial deposit.  In  addition  to  the  erosion  channels  in  which  the  streams 
flow  when  at  their  average  height,  we  find  most  of  the  streams  bordered  by 
one  or  more  terraces  at  higher  level.  The  terraces  consist  of  a  somewhat 
horizontal  portion,  or  shelf,  ending  in  a  rather  steep  bank  or  blufl^  facing- 
the  stream.  The  material  of  most  of  the  terraces  is  some  form  of  water 
drift,  but  sometimes  it  is  till.  In  a  few  places  where  the  channel  proper 
lies  in  easily  eroded  sand,  there  are  no  terraces  above  the  banks  of  the 
channel  of  erosion.  This  occurs  when  erosion  and  deposition  are  nearly 
equal,  and  when  deposition  is  the  greater. 

River  terraces  may  be  divided  into  two  classes. 

1.  Terraces  of  river  erosion  in  drift  which  was  not  deposited  by  the 
rivers  themselves.  The  till  and  the  marine  glacial  and  lacustral  sediments 
were  deposited  under  conditions  independent  of  the  streams  which  subse- 
quently began  to  flow  in  the  valleys  of  deposition,  and  the  agencies  by 
which  they  were  deposited  could  not  have  formed  a  series  of  terraces  to 
which  the  streams  bear  a  causal  relation.  River  terraces  in  these  forma- 
tions, or  in  blown  sand,  must  be  due  to  erosion  by  the  rivers.  They  are  as 
plainly  formed  by  erosion  on  the  land  as  a  beach  cliff'  is  caused  by  waves 
and  currents.     The  erosion  terraces  of  Maine  correspond  to  the  rock  bluff's 


(52  GLACIAL  GRAVELS  OF  MAINE. 

which  border  the  streams  of  the  Mississippi  Valley  and  the  Rocky  Mountains, 
except  that  they  have  been  excavated  in  imconsolidated  di-ift  and  within 
a  relatively  short  time.  Below  the  contour  of  230  feet  all  the  higher 
terraces  which  border  the  rivers  of  Maine  are  the  result  of  the  erosion 
of  till,  blown  sand,  the  marine  sands  and  clays,  oi-  the  glacial  sand  and 
ffravel.  Erosion  of  these  formations,  especially  of  the  marine  clays,  has 
been  efiPected  on  a  grand  scale.  In  many  places  the  marine  clays  have 
been  eroded  into  forms  somewhat  resembling  the  "bad  lands"  of  the  West. 
When  a  ravine  once  begins  to  form,  it  rapidly  extends  itself  back  into  the 
clay.  I  have  observed  several  ra-sdnes  which,  within  five  years,  extended 
themselves  from  one-eighth  to  one-fourth  of  a  mile  and  to  a  depth  of  10  or 
more  feet.  These  were  formed  where  there  were  no  permanent  streams, 
and  were  wholly  due  to  the  wash  of  the  rains.  In  the  regions  covered  by 
the  marine  clays  the  streams  having  constant  flow  are  bordered  b}'  cliffs  of 
erosion,  just  like  the  narrow  ra^^nes,  only  the  cliff's  are  situated  much 
farther  from  one  another,  sometimes  from  1  to  3  miles.  The  ravines  and 
cirques  of  erosion  are  so  characteristic  of  the  clay-covered  regions  that  by 
them  one  can  recognize  most  of  that  part  of  Maine  which  was  under  the 
sea,  even  when  deeply  covered  by  snow.  The  till,  being  much  harder  to 
erode  than  the  sedimentary  drift,  rarely  shows  cliff's  of  erosion  at  levels 
above  the  channel  proper,  except,  where  the  flow  of  the  stream  in  time  of 
flood  is  very  much  greater  than  the  ordinary  flow.  Hence  the  scenery  in 
the  areas  covered  by  till  is  very  diff'erent  from  that  of  the  clay  regions. 
The  methods  of  terrace  erosion  will  be  more  fully  considered  hereafter. 

2.  Terraces  composed  chiefly  of  valley  sediments.  The  simplest  case 
is  that  of  the  present  flood-plain  terraces.  They  rise  to  only  a  moderate 
height  above  the  present  beds  of  the  streams,  and  now  and  then  they  are 
overflowed  in  time  of  high  water.  The  drift  of  the  flood  plain  is  of  very 
composite  origin.  Part  of  it  is  usually  the  uneroded  remains  of  a  sheet  of 
drift  laid  down  previous  to  the  flow  of  the  stream  at  its  present  level — either 
till  or  the  marine  beds  or  valley  drift  deposited  near  the  close  of  the  Glacial 
period.  Part  of  it  is  of  recent  origin,  consisting  of  sediment  deposited  by 
the  stream  in  time  of  flood  or  of  matter  brought  down  by  the  rains  from  the 
higher  terraces  and  the  hillsides.  Wherever  deposition  equals  or  exceeds 
erosion,  the  flood  plain  is  not  nominally  bordered  by  steep  cliffs  or  banks  of 
erosion,  but  it  simply  extends  to  the  sides  of  the  valley,  sometimes  being 


EIVER  TERRACES.  63 

perceptibly  higher  near  the  stream.  In  other  words,  the  valley  is  filhng 
with  sediment.  This  is  the  condition  of  the  stream  and  valley  at  the  delta, 
provided  the  flow  of  water  is  sufficient  to  cover  the  whole  valley  from  side 
to  side.  In  a  few  places  this  is  the  present  condition  of  tlie  valleys,  as,  for 
instance,  the  valley  of  the  Crooked  River  for  a  few  miles  north  of  Sebago 
Lake.  Most  of  the  more  level  portions  of  the  larger  valleys  of  Maine 
must  have  been  in  this  condition  at  the  close  of  the  Ice  age. 

A  strict  classification  would  distinguish  the  flood  plain  of  erosion  from 
that  of  deposition.  Practically  the  two  processes  are  intimately  blended. 
On  the  steeper  slopes  the  flood  plain  is  almost  always  due  to  erosion  in 
times  of  flood;  on  the  gentler  slopes  it  is  composed  wholly  or  in  part  of 
matter  deposited  by  the  flood  waters.  It  is  often  difficult  to  determine 
which  of  the  two  processes  has  been  more  active.  In  field  use,  the  term 
"flood  plain"  imphes  the  lowest  river  terrace  which  is  now  overflowed  by 
the  river  in  time  of  flood,  without  regard  to  the  origin  of  the  terrace. 

Below  the  highest  postglacial  level  of  the  sea  (230  feet),  we  find  the 
larger  streams  bordered  by  a  rather  narrow  flood  plain,  above  which  rise 
one  or  more  erosion  terraces  in  the  marine  beds,  or  in  the  glacial  sands  and 
gravels,  or  sometimes  in  till.  Soon  after  we  rise  above  230  feet  we  find 
one  or  more  river  terraces  in  the  so-called  valley  drift.  In  addition  to  the 
marginal  terraces,  several  of  the  valleys  show  large  ridges  lying  along 
the  axis  of  the  valley.  The  largest  and  longest  of  these  that  I  have 
observed  were  found  in  the  Kennebec  Valley  above  Solon,  in  the  valley  of 
the  Little  Androscoggin  above  South  Paris,  and  in  the  Piscataquis  Valley 
above  Abbott.  The  number  of  marginal  terraces  varies.  In  general,  the 
top  of  the  central  ridge  has  nearly  the  same  elevation  as  the  higher  mar- 
ginal terraces.  Both  Jackson  and  Hitchcock  report  terraces  in  the  upper 
Kennebec  Valley  at  elevations  such  that  they  must  be  higher  than  the 
central  ridges.  These  highest  terraces  are  so  obscure  that  I  hesitate  to 
"call  them  terraces. 

KECENT  EROSION  OF  THE  VALLEY  ALLUVIUM  AND  OF  THE  '  GLACIAL  SANDS  AND 

GRAVELS. 

Before  discussing  the  origin  of  the  higher  river  terraces,  it  is  necessary 
to  inquire  what  sort  of  geological  work  is  now  going  on  in  the  river  valleys. 
We  can  not  declare  that  the  higher  terraces  above  the  flood  plain  are  due 


64  GLACIAL  GRAVELS  OF  MAIXE. 

to  erosion  (the  common  theoiy)  until  it  is  proved  that  erosion  is  now  going 
on  at  such  a  rate  as  to  justify  the  induction  that  tlie  terraces  could  have 
been  eroded  within  the  time  that  has  elapsed  since  the  Valley  Drift  period. 
Thus,  for  instance,  the  Kennebec  and  Sandy  rivers  are  bordered  for  many 
miles  by  bluffs  or  terraces  50  to  80  feet  high,  and  between  these  bluffs  lies 
a  valley  one-fourth  to  three-fourths  of  a  mile  wide.  On  the  erosion  theory, 
there  is  a  very  lai-ge  amount  of  denudation  and  transportation  to  be  accounted 
for.  We  have  already  noted  that  areas  of  the  marine  sands  and  clays  from 
1  to  even  5  miles  in  diameter  have  been  eroded  by  rains  and  streams  to  a 
depth  of  10  to  70  feet  or  more. 

According  to  a  common  theory  of  stream  erosion,  the  terraces  were 
eroded  directly  by  the  rivers  as  they  wandered  back  and  forth  over  their 
flood  plains,  or  by  their  lateral  branches.  On  this  theory  the  base  of  every 
bluff  or  terrace  was  once  Avashed  by  the  river  or  its  tributaries,  at  least  in 
time  of  flood.  This  process  of  erosion  by  meandering  can  be  seen  in  oper- 
ation in  many  valleys,  and  is  no  doubt  a  common,  and  in  greater  or  less 
degree  a  universal,  process.  But  there  is  in  operation  in  Maine  a  process 
which  is  often  far  more  efficient  in  eroding  wide  valleys  than  meandering. 

We  have  seen  that  the  upper  stratum  of  the  valley  drift  is  usually 
coarser  than  the  lower.  Hence  the  surface  waters  soak  readily  through  the 
porous  upper  stratum  until  they  reach  the  rather  impervious  underclay. 
They  then  seep  laterally  tlu-ough  the  basal  layers  of  the  sand  and  gravel 
and  along  the  top  of  the  clay  until  they  find  exit  in  the  form  of  boiling 
springs.  The  same  thing  happens  at  the  plains  of  glacial  sand  and  gravel, 
only  in  this  case  the  water  is  generally  arrested  by  the  till.  Thus,  boiling 
springs  often  reveal  the  presence  of  glacial  gravel  hidden  beneath  marine 
clay.  The  reasoning  is  as  follows:  Large  boiling  springs  are  rare  in  the 
till,  unless  for  a  short  time  while  the  snow  is  thawing  in  the  springtime.  If 
such  a  spring  issues  from  a  suspected  ridge,  the  ridge  is  more  likely  to  be 
glacial  gravel  than  till.  The  decisive  test  is  funiished  by  the  stones  found" 
in  the  boiling  spring  and  its  outlet,  which  will  be  well  rounded  if  the  spring 
issues  from  a  mass  of  glacial  gravel,  and  will  not  be  the  ordinary  tillstones. 

A  fine  instance  of  recent  erosion  by  springs  can  be  seen  a  short  dis- 
tance south  of  Solon  Village.  The  plain  of  the  valley  drift  which  occupies 
the  valley  of  the  Kennebec  River  here  extends  for  one-half  mile  or  more 
east  of  the  river.     Back  from  the  river  at  varying  distances  up  to  one- 


OEIGIN"  OF  EIVEE  TEEEACES.  65 

fourth  of  a  mile  is  a  crooked  bluff.  At  one  place  the  bluff  makes  a  very 
reentrant  curve  and  borders  a  cirque,  locally  known  as  the  "Hopper  hole." 
There  can  be  no  doubt  as  to  the  origin  of  this  bluff.  Within  a  few  years 
preceding-  1878  (the  date  of  my  visit  to  the  place),  the  subterranean  waters 
had  eroded  a  ravine  10  to  70  feet  deep  and  had  cut  back  into  the  plain  for 
300  feet.  In  spite  of  the  most  strenuous  efforts  to  stop  the  washout  in 
order  to  save  the  public  road,  it  had  been  necessary  to  change  the  road 
twice.  Large  piles  of  brush,  logs,  bowlders,  and  various  kinds  of  rubbish 
had  been  thrown  into  the  ravine.  The  flow  had  at  times  been  tempo- 
rarily stopped,  but  the  waters  collected  as  behind  a  dam,  and  the  porous 
sand  and  gravel  over  considerable  areas  became  permeated  by  water 
under  pressure  until  a  considerable  part  of  the  gravel  plain  was  in  the 
semiliquid  condition  of  quicksand.  Finally  either  the  dam  was  swept 
out  of  the  ravine  or  the  sand-and-gravel  plain  was  washed  away  around 
the  ends  of  the  dam.  When  once  the  sand  and  gravel  was  in  motion,  it 
passed  readily  iiito  the  river,  very  little  being  dropped  on  the  way.  The 
work  of  the  river  consisted  in  carrying  away  the  sediment  furnished  it  by 
the  springs.  Here  is  an  unmistakable  case  of  steep  cliffs  or  bluffs  of 
erosion  formed  at  a  considerable  distance  from  a  river,  not  by  the  meander- 
ing of  the  river  but  by  rains  and  boiling  springs,  the  sui-face  wash  being 
small  compared  with  the  action  of  the  subterranean  waters. 

The  great  amount  of  erosion  effected  by  subterranean  waters  as  they 
rapidly  flow  out  of  a  porous  mass  of  sand  and  gravel  has  recently  been 
demonstrated  at  a  point  5  or  6  miles  northeast  from  Cherryfield.  The  site 
of  the  washout  is  at  a  boiling  spring  which  had  long  been  known  to  issue 
from  the  southern  edge  of  the  great  glacial  sand  and  gravel  plains  of 
Deblois  and  Columbia.  The  plain  here  ends  in  a  steep  bhxff  facing  the 
south,  and  rises  50  feet  above  the  plain  of  marine  clay  at  its  base.  At  the 
time  of  the  washout  a  ravine  100  feet  long,  26  feet  wide  at  its  base,  and  on 
the  average  30  feet  deep,  had  been  cut  back  into  the  gravel  plain,  and  the 
eroded  matter  had  been  spread  over  an  area  of  2  or  3  acres  at  varying 
depths  up  to  4  feet.  No  surface  stream  is  to  be  found  on  the  gravel 
plain  near  this  place,  and  the  cause  of  the  eruption  lay  beneath  the  plain. 
During  the  winter  of  1885-86  there  was  a  thaw,  during  which  a  large 
amount  of  snow  melted.  Soon  after  there  came  a  remarkable  storm.  The 
precipitation  took  the  form  of  snow  in  the  interior  of  tlie  State,  but  over  a 

MON  XXXIV 5 


66  GLACIAL  GEAVELS  OF  MAINE. 

belt  20  to  40  miles  wide  next  the  coast  there  was  a  heavy  fall  of  rain  and 
sleet.  It  is  known  as  the  "ice  storm,"  because  thick  ice  g-athered  on  the 
trees  and  broke  down  thousands  of  them,  besides  numberless  branches. 
The  next  July  after  the  washout  the  matter  eroded  from  the  plain  could  be 
seen  overlying  great  mimbers  of  limbs  that  had  recently  been  broken  ofP 
and  the  tops  of  several  small  trees  recently  bent  to  the  ground.  The  wash- 
out, therefore,  must  have  occurred  during  or  soon  after  the  ice  storm.  Evi- 
dently the  unusual  rush  of  subterranean  water  was  due  to  the  snow  melted 
dm-ing  the  thaw,  assisted  by  the  rains  of  the  subsequent  ice  storm.  The 
water  seeped  down  through  the  porous  gravel  until  it  was  stopped  by  the 
till  or  solid  rock,  and  it  could  then  find  exit  onh'  bv  flowing  out  from  the 
side  of  the  gravel  plain,  Avhich  it  did  so  rapidly  as  to  effect  the  large  erosion 
above  stated. 

We  thus  have  not  onl}-  the  ordinary  and  unceasing  erosion  of  porous 
sediments  by  sjDi'ings  boiling  up  through  them,  but  also  from  time  to  time 
these  extraordinary  outbursts.  The  most  destructive  outbursts  take  place 
in  winter  and  spring.  In  Maine  the  ground  ordinarily  freezes  in  winter  to 
a  depth  of  2  or  3  feet,  and  it  must  often  happen  that  the  smaller  outlets  by 
which  the  seeping  waters  escape  will  be  frozen  solid.  The  waters  thus 
temporarily  dammed  will  accumulate  until  considerable  pressure  is  attained 
and  will  help  to  increase  the  velocity  of  the  escaping  water  when  at  length 
the  ground  thaws  and  a  passage  is  forced.  The  dams  or  gorges  which  often 
form  in  rivers  when  the  ice  breaks  up  in  the  spring  must  have  the  same 
effect  on  porous  valley  alluvium.  The  pressure  of  the  water  above  the  ice 
dam  must  sometimes  cause  a  raj)id  seepage  through  coarse  gravel  and  cob- 
bles and  the  formation  of  erosive  boiling  springs  at  points  below  the  dam. 
As  noted  elsewhere,  the  erosive  power  of  a  stream  when  flowing  out  of  a 
mass  of  gravel  is  much  greater  than  that  of  the  same  stream  when  sweep- 
ing past  the  base  of  a  body  of  the  gravel.  The  remarkable  amount  of 
erosion  of  osar-plains  by  even  small  streams  is  well  illustrated  neai-  Knox, 
between  Canton  and  Livermore,  and  between  Rumford  and  North  Wood- 
stock, as  described  elsewhere.  It  is  noticeable  that  moderately  coarse 
gravel  plains  are  eroded  even  more  than  fine  sand. 

Universally,  so  far  as  my  observation  goes,  the  narrow  ridges  of  glacial 
gravel  (kames  and  osars)  have  resisted  erosion  better  than  the  large  plains. 
This  fact  seemed  unaccountable  until  I  besfan  to  investig-ate  the  action  of 


OEIGIN  OF  EIVEE  TBERACES.  67 

subterranean  waters.  It  then  became  evident  that  erosion  is  often  more 
active  from  within  than  from  without.  Large  boiUng-  spi'ings  can  form  only 
where  there  is  a  large  surface  of  porous  matter,  since  the  seepage  of  such 
matter  varies  with  the  surface  exposed  to  the  rains.  It  follows  that  this 
kind  of  erosion  was  formerljr  more  rapid  tlian  at  present,  since  there  was 
then  a  larger  surface  exposed.  In  case  of  some  of  the  osar-plains  the 
amount  of  subterranean  water  must  once  have  been  two  or  more  times 
the  present  suppl;^'.  In  this  connection  it  should  be  noted  that  the  rainfall 
of  Maine  is  from  40  to  56  inches  annually. 

ORIGIN    OF    THE    HIGHER    RIVER    TERRACES    OF    THE    VALLEY    DRIFT. 

The  following  considerations  bear  on  this  disputed  question : 

1.  The  facts  stated  above,  and  elsewhere,  prove  that  the  larger  plains 
of  sand  and  gravel  are  now  being  rapidly  eroded  at  considerable  distances 
from  streams  by  rains  and  subterranean  waters.  In  many  cases  it  can  be 
proved  that  these  agencies  are  more  efficient  in  eroding  high-level  terraces 
than  is  the  meandering  stream. 

2.  Many  of  the  river  terraces  which  are  situated  above  230  feet  extend 
continuously  down  then-  valleys  until  they  end  in  terraces  in  the  marine 
clays.     But  the  latter  are  plainly  due  to  erosion. 

3.  The  marine  beds  have  been  eroded  over  areas  1  to  3  and  even  5 
miles  broad.  A  less  amount  of  erosion,  though  of  coarser  matter,  will 
account  for  all  the  river  terraces  above  the  former  sea  level. 

4.  The  upper  portion  of  the  valley  drift  is  so  generally  coarser  than 
the  lower  that  the  conditions  for  rapid  erosion  by  subterranean  waters  are 
afforded  by  most  of  the  larger  valleys  of  New  England. 

6.  The  formation  of  terraces  and  bluffs  of  erosion  not  distinguishable 
in  form  from  the  ordinary  river  terrace  has  been  observed  in  recent  time. 

Two  theories  as  to  the  origin  of  the  higher  river  terraces  of  valley 
drift  demand  examination :  One  is  the  erosion  theory,  according  to  which 
the  steep  bluffs  are  the  result  of  the  partial  erosion  of  a  sheet  of  sediment 
which  once  extended  across  the  valley.  The  other  is  the  theory  suggested 
by  Prof  J.  D.  Dana,  to  account  for  the  terraces  of  the  upper  Connecticut 
Valley.i 

According  to  the  latter  theory,  the  terraces  were    deposited    at  the 

'The  flood  of  the  Connecticut  Valley  glacier,  Am.  Jour.  Sci.,  3d  series,  vol.  23,  pp.  87, 179,  360, 1882. 


68  GLACIAL  GRAVELS  OF  MAINE. 

margin  of  a  river  which  then  filled  the  whole  valley  to  the  height  of  the 
terraces.  The  water  rose  by  successive  stages,  and  the  central  parts  of  the 
valleys  were  never  filled  by  a  sheet  of  drift,  as  postulated  by  the  erosion 
theory.  The  erosion  theory  postulates  a  water  channel  along  the  valley, 
and  a  pretty  large  one,  but  by  no  means  so  large  as  the  whole  space 
included  between  the  terraces.  Professor  Dana's  theory  requires  several  or 
many  times  the  amount  of  water  required  by  the  erosion  theory,  i.  e.,  the 
stream  must  have  been  swift  enough  to  keep  its  supposed  channel  (the 
space  between  the  terraces)  free  of  sediment. 

The  presence  in  several  of  the  river  valleys  of  a  central  ridge,  so 
evidently  an  uneroded  portion  of  a  once  continuous  plain,  strongly  favors 
the  erosion  theory  as  to  the  formation  of  the  broader  ten-aces  of  valley 
drift  up  to  the  level  of  the  central  ridges.  This  includes  most  of  the  ter- 
races. Perhaps  I  have  not  seen  the  terraces  at  very  high  level,  noted  by 
Jackson  and  Hitchcock  in  the  Kennebec  Valley,  though  I  looked  for  them; 
but  I  have  notes  of  a  few  narrow  terraces  above  the  erosion  terraces  which 
seemed  to  have  been  deposited  in  substantially  their  present  shapes.  Their 
material  resembles  that  of  the  glacial  gravels,  but  is  not  much  rounded. 
These  terraces  were  at  first  judged  to  be  ordinary  glacial  gravels,  but  they 
preserve  so  nearly  the  same  longitudinal  slope  as  the  valley  drift  proper  as 
to  give  good  ground  for  suspicion  that  they  were  formed  at  the  margin  of 
the  valleys,  as  suggested  by  Professor  Dana.  But  if  so,  it  is  not  certain 
that  they  were  formed  at  the  margin  of  a  great  river  filling  the  whole  valley. 
During  the  final  melting,  the  ice  in  the  valleys — if  we  may  follow  the  anal- 
ogies of  ordinary  glaciers  flowing  in  valleys — might  sometimes  melt  fastest 
on  the  side  next  to  the  warmed  hills.  A  stream  would  form  in  these  mar- 
ginal depressions,  and  the  sediments  deposited  in  them  would  now  appear 
as  terraces.  These  narrow  high-level  terraces  may  therefore  be  of  semi- 
glacial  origin,  i.  e.,  formed  between  the  bare  hills  on  the  one  side  and  the 
ice  of  the  valley  on  the  other. 

SUMMARY. 

The  channels  of  the  rivers  of  valley  drift  time  have  been  g-reatly 
deepened  and  widened,  partly  by  the  direct  action  of  the  rivers  upon  the 
valley  drift  which  then  filled  up  the  lower  parts  of  the  larger  valleys, 
partly  by  the  rains  and  by  subterranean  waters.     In  this  process  terraces 


ORIGIN  OF  RIVER  TERRACES.  69 

have  been  foi-med;  and  while  most  of  the  terraces  are  due  to  the  carving 
and  partial  erosion  of  alluvinm  previously  laid  down,  yet  a  residue  remains 
where  naiTow  terraces  may  have  been  deposited  in  substantially  their 
present  shapes,  either  at  the  sides  of  an  ordinary  river  of  great  size  or  along 
the  margins  of  a  mass  of  ice  filling  the  central  parts  of  the  valley.  The 
question  will  be  more  fully  discussed  later  (see  Chapter  VI). 


CHAPTER   IV. 

GENERAL  DESCRIPTION  OF  THE  SYSTEMS  OF  GLACIAL 

GRAVEL. 

According-  to  the  nomenclature  here  adopted,  a  system  comprises  the 
sediments  deposited  by  a  single  glacial  river  with  its  tributary  and  delta 
branches. 

VANCEBORO  SYSTEM. 

Two  well-defined  osars  converge  at  Vanceboro  station.  One  has  been 
traced  for  about  IJ  miles  northwest  of  the  station,  as  a  low  ridge,  scarcely 
rising  above  a  bog.  The  gravel  is  distinctly  waterworn,  and  the  ridge 
would  naturally  extend  farther  north,  but  such  extension  has  not  yet  been 
traced.  The  railroad  station  is  built  on  the  gravel  of  this  ridge.  The 
other  osar  is  a  two-sided  ridge,  from  10  to  30  feet  high,  which  follows  the 
west  shore  of  the  Lower  Chiputneticook  Lake  for  somewhat  more  than  a 
mile  north  of  Vanceboro,  when  it  seems  to  end  in  a  bog  near  the  lake.  The 
shore  of  the  lake  here  bends  toward  the  northwest,  and  the  northern  exten- 
sion of  this  system,  if  there  is  any,  would  naturally  be  found  on  the  north 
side  of  the  lake  in  New  Brunswick.  Numerous  persons  have  reported  to 
me  that  "horsebacks"  of  gravel  are  found  in  the  valley  of  Palfrey  Brook, 
but  I  can  not  be  certain  from  the  descriptions  whether  these  are  till  or  true 
glacial  gravel.  A  horseback  on  Eel  River,  in  York  County,  New  Bruns- 
wick, has  also  been  reported.  Mr.  R.  Chalmers  describes  it^  as  a  large 
ridge,  probably  beginning  in  Maine  and  thence  extending  southeastwardly 
along  the  valleys  of  Bull  Creek  and  Eel  River  to  First  Eel  Lake,  where  it 
disappears  under  the  lake.  Mr.  Chalmers's  description  shows  this  to  be  an 
osar.  So  large  a  ridge  implies  a  glacial  river  of  considerable  size.  As  it 
does  not  seem  to  end,  according  to  Mr.  Chalmers's  description,  in  a  delta- 

'  Report  on  the  surface  geology  of  western  New  Brunswick :  Geological  and  Natural  History- 
Survey  aud  Museum  of  Canada,  Report  of  Progress  for  1882-83-84,  p.  25  GG,  Montreal,  1885. 
70 


VANCEBOEO  SYSTEM. 


71 


plain  at  First  Eel  Lake,  the  river  would  naturally  have  flowed  farther  south 
or  southeast.  If  so,  the  Eel  River  osar  may  prove  to  be  a  continuation  of 
one  of  the  osars  that  unite  at  Vanceboro. 

A  short  distance  north  of  the  railroad  bridge  at  Vanceboro  is  a  small 
and  rather  level-topped  plain  of  sand  and  fine  gravel  which  extends  west- 
ward from  the  main  osar  ridge.  It  ends  in  a  steep  bank,  and  is  quite  regu- 
larly stratified,  the  strata  dipping  outward.  The  material  is  somewhat 
coarser  near  the  main  ridge  than  at  the  edges,  and  therefore  the  deposit 
presents  the  external  appearance  of  a  small  delta  ending  in  sand,  showing 
that  the  currents  were  not  wholly  checked. 

Just  south  of  this  plain  the  St.  Croix  River  bends  to  the  westward  and 
crosses  the  line  of  the  osar.  There  is  a  short  gap  in  the  ridge  at  this  point, 
perhaps  due  in  part  to  erosion  by  the  river.  A  ridge  begins  a  few  rods 
sou-th  of  the  railroad  sta- 
tion  (near  where  the  two  ^*'  "^^"^ 
glacial  rivers  united),  and 
thence  a  well-defined  ridge 
or  series  of  ridges  is  formed 
along  the  St.  Croix  for 
about  5  miles,  it  being 
most  of  the  way  on  the 
west  side  of  the  river.  At 
the  mouth  of  Trout  Brook  the  river  makes  an  abrupt  bend  westward, 
and  the  course  of  the  gravel  system  is  uncertain.  Large  sand-and-gravel 
plains  are  reported  by  Prof.  Gr.  F.  Mathew,'  near  Lynnfield,  Charlotte 
County,  New  Brunswick.  I  did  not  personally  explore  the  valley  of  the 
St.  Croix  for  several  miles  south  of  A-^anceboro,  and  my  marking  of  the 
probable  course  of  this  glacial  river  as  extending  from  the  mouth  of  Trout 
Brook  southeastward  past  Mud  Lake  to  Lynnfield,  where  it  would  naturally 
deposit  delta-plains,  is  provisional.  The  Lynnfield  plains  ajjpear  to  be  con- 
siderably above  the  contour  of  225  feet,  and  this  glacial  river  may  have 
deposited  gravels  south  or  southeast  of  them,  perhaps- down  the  valley  of 
the  Digdequash  River. 


closinir  lakelet,  Vanceboro 


■  Report  on  the  superficial  geology  of  southern  New  Brunswick :  Geological  Survey  of  Canada, 
Report  of  Progress  for  1877-78,  pp.  13-14  ee,  Montreal,  1879. 


72  GLACIAL  GRAVELS  OF  MAINE. 

DYER    PLANTATION    SYSTEM. 

An  osar  from  20  to  40  feet  high  extends  from  near  the  mouth  of  Big- 
Simsquish  Stream  southward  nearly  parallel  with  tlie  St.  Croix  River  for 
about  3  miles,  in  Dyer  Plantation,  Washington  County.  It  then  takes 
the  form  of  somewhat  discontinuous  low  bars  and  terraces,  which  perhaps 
are  a  poorly  defined  osar-plain.  This  extends  past  the  enlargement  of  the 
St.  Croix  River  known  as  Loon  Bay  to  the  mouth  of  the  Canoose  Stream, 
where  the  system  crosses  into  New  Brunswick  and  sends  out  two  tongues 
of  sand  and  gi-avel  for  about  6  miles  southeastward,  one  on  each  side  of 
Basswood  Ridge.  I  saw,  in  1879,  only  a  portion  of  these  plains.  They 
a2Dpeared  to  be  rather  level  on  the  top,  with  the  exception  of  a  few  two- 
sided  ridges  here  and  there  rising  above  the  rest  of  the  plain.  They  present 
the  external  features  of  a  delta-plain,  either  marine  or  deposited  in  a  glacial 
lake. 

For  several  miles  above  the  mouth  of  Little  Simsquish  Stream  1  could 
find  no  glacial  gravel  on  the  west  side  of  the  St.  Croix,  but  could  see  across 
the  river  on  the  Canadian  side  considerable  gravel  of  some  kind  in  the  form 
of  teiTaces.  For  about  1  mile  above  the  mouth  of  Scotts  Brook  the  gravel 
near  the  St.  Croix  was  very  nearly  in  shape  that  of  tillstones.  This  makes 
it  highly  probable  that  the  Vanceboro  system  does  not  continue  in  the  St. 
Croix  Valley  below  the  mouth  of  Trout  Brook  so  as  to  connect  with  the 
Dyer  system.  I  could  find  no  trace  of  this  glacial  river  to  the  north  or 
west  of  the  mouth  of  Big  Simsquish  Stream,  unless  a  small  plain  covered 
by  a  thin  sheet  of  sand  may  have  been  deposited  by  it.  This  plain  is  over- 
grown with  pines,  and  is  situated  not  far  from  Scotts  Brook,  about  half^vay 
from  Lambert  Lake  to  the  mouth  of  that  stream.  The  country  is  a  dense 
wilderness,  and  one  might  pass  very  near  a  large  osar  and  not  see  it. 

The  osar  in  Dyer  contains  many  rounded  bowlderets  and  some  bowl- 
ders. In  many  places  the  lateral  slopes  are  very  steep.  According  to 
Anson,^  the  elevation  of  the  head  of  Canoose  Rips  is  211  feet;  that  of  the 
foot  of  Rocky  Rips,  near  the  north  end  of  the  Dyer  osar,  as  here  described, 
is  227  feet.  The  plains  of  the  Canoose  Valley  and  those  near  Basswood 
Ridge  are  thus  shown  to  be  not  far  above  the  highest  of  the  beaches. 

'The  Water  Power  of  Maine,  by  Walter  Wells,  p.  115,  Augusta,  1869. 


SYSTEMS  OF  GLAOIAL  GRAVELS.  73 

BARING-PEMBROKE  SYSTEM. 

A  ridge  of  glacial  gravel  comes  from  the  north  of  the  northern  bank 
of  the  St.  Croix  River  a  short  distance  west  of  the  bridge  of  the  St.  Croix 
and  Penobscot  Railroad  Company,  at  Baring.  Directly  opposite,  on  the 
southern  bank,  the  ridge  begins  again,  and  probably  it  was  once  continu- 
ous across  the  bed  of  the  stream;  but  if  so,  it  has  been  considerably  washed 
away.  A  series  of  ridges  separated  by  gaps  extends  from  Baring  south- 
ward over  a  low  divide,  and  thence  along  the  valley  of  Moosehorn 
Stream.  Farther  south  the  system  takes  the  form  of  a  rather  continuous 
level-topped  plain,  which  presents  the  external  features  of  a  marine  delta- 
plain;  but  1  or  2  miles  north  of  Pennamaquan  Lake,  in  Charlotte,  the  sys- 
tem changes  to  a  seiies,  nearly  a  mile  wide,  of  broad  reticulated  ridges 
about  100  feet  high,  inclosing  several  deep  kettleholes.  The  gravel  passes 
into  the  northern  end  of  Pennamaquan  Lake  as  a  long  gently-sloping  bar, 
and  within  2  miles  reappears  on  the  western  shore  of  the  lake,  and  thence 
the  series  is  found  along  the  lake  and  Pennamaquan  Stream  to  its  mouth 
in  Pembroke.  Toward  the  south  the  ridges  become  shorter  and  the  gaps 
somewhat  longer — indeed,  some  of  the  ridges  are  so  short  as  almost  to  be 
lenticular  hummocks.  Unless,  perhaps,  at  Pennamaquan  Lake  and  at  the 
top  of  the  col  in  the  southern  part  of  Baring,  the  gaps  in  this  system  seldom 
exceed  one-fourth  of  a  mile.  The  country  traversed  by  this  system  is  cov- 
ered by  marine  clay.  An  excavation  in  this  gravel  ridge  made  a  short  dis- 
tance south  of  Baring  Village  showed  the  ridge  to  be  covered  by  3  feet 
of  clay  containing  marine  fossils,  and  a  number  of  bowlders  having  the 
ordinary  till  shapes  rest  on  the  clay  directly  above  the  gravel. 

The  northern  connections  of  this  system  are  obscure.  D.  F.  Maxwell, 
a  civil  engineer  of  St.  Stephen,  New  Brunswick,  reports  sand-and-gravel 
deposits  in  the  valley  of  the  Moannes  Stream,  extending  about  4  miles 
north  from  Baring,  and  these  are  probably  a  part  of  this  system.  Gravels 
are  reported  at  Chiputneticook  Falls,  St.  Croix  River.  Possibly  this  system 
is  a  continuation  of  the  Dyer  system,  but  I  mark  them  provisionally  as 
independent  systems. 

HOULTON-DENNYSVILLE    SYSTEM. 

This  important  osar  system  appears  to  begin  a  few  miles  north  of  the 
divide  between  the  waters  flowing  northward  into  the  Aroostook  River  and 


74  GLACIAL  GRAVELS  OF  MAINE. 

tliose  flowing-  south  and  east,  at  an  elevation  of  about  900  feet.  In  the 
eastern  part  of  T.  9,  E..  4,  Aroostook  County,  a  two-sided  ridge  extends 
for  about  3  miles  along  the  east  side  of  the  Aleg'wanus  or  Blackwater 
River,  a  stream  which  flows  northwesterly  into  the  Ai-oostook.  The  ridge 
has  rather  steep  lateral  slopes,  and  is  from  10  to  30  feet  high.  On  the  sur- 
face it  appears  to  be  composed  of  till,  but  on  dijjjging  down  2  or  3  feet, 
true  water-washed  gravel  is  revealed.  The  pebbles  are  only  slightly 
rounded,  yet  the  finest  debris  has  been  plainly  removed  by  gentle  currents, 
and  therefore  the  deposit  is  seen  to  be,  not  unmodified  till,  but  the  residue 
after  the  action  of  Avater  has  removed  the  finest  portion  of  the  till  and  has 
rounded  and  polished  the  larger  fragments  a  very  little.  The  ridge  is  here 
composed  of  fragments  of  sedimentary  rocks,  which  readily  weather  near 
the  surface  of  the  ground,  so  as  to  lose  their  waterworn  surfaces  and  to 
resemble  closely  the  stones  of  the  upper  layers  of  till.  After  an  apparent 
gap  in  the  system  of  more  than  a  mile,  another  ridge  is  found,  extending 
eastward,  which  is  said  to  reach  the  northwest  corner  of  Littleton,  where 
the  system  takes  a  more  southerly  course  to  Carys  Mills,  a  short  distance 
west  of  Houlton  Village.  In  this  part  of  its  course  it  several  times  crosses 
low  divides,  and  thtis  passes  from  one  valley  into  another;  and  there  are 
several  gaps  in  the  system. 

Prof  C.  H.  Hitchcock  writes  concerning  this  osar  as  follows:^  "A 
short  distance  west  of  Houlton  the  same  horseback  reappears,  being  in 
one  place  90  feet  high.  The  material  of  the  ridge  is  sand,  gravel,  and 
bowlders,  indistinctly  stratified.  The  sand  of  this  horseback  is  black,  and 
there  is  no  similar  sand  anywhere  else  in  the  county  south  of  Houlton." 

On  the  same  page  is  given  a  figure  showing  the  internal  structure  of 
the  "horsebacks."  Occasionally  I  have  observed  sections  such  as  that  given 
in  Professor  Hitchcock's  figure,  but  usually  the  osars  have  a  more  arched 
stratification  in  the  cross  section.  Not  far  north  of  Carys  Mills  the  osar 
extends  into  a  broad  ridge  or  plain,  with  some  reticulated  ridges  as  outlets. 
This  great  abundance  of  gravel  is  found  at  the  southern  end  of  a  long  slope, 
which,  for  25  miles,  has  an  average  fall  of  about  20  feet  per  mile.  The 
pebbles  and  cobbles  are  very  well  rounded  at  this  point,  and  a  much  larger 
proportion  of  them  are  granitic  than  at  the  northern  end  of  the  system. 
From  Carys  Mills  the  osar  continues  as  a  large  ridge  for  several  miles, 


'  Preliminary  report  upon  the  natural  history  and  geology  of  the  State  of  Maine,  p.  273,  1861. 


HOULTON^-DENNYSVILLE  SYSTEM.  75 

through  Hoclgdon,  followiug  the  south  branch  of  the  Meduxnikeag  River. 
In  Gary  Plantation  the  system  turns  southeastward,  crosses  to  the  east  of 
the  Calais-Houlton  road,  and  continues  southward  for  several  miles  in  a 
valley  nearly  parallel  with  that  road.  In  this  part  of  its  course  it  crosses 
a  divide  at  least  75  feet  above  Carys  Mills,  and  for  several  miles  in  Hodg- 
don  it  consists  of  a  series  of  low  bars  separated  by  short  gaps,  in  part  due 
to  erosion.  Near  the  north  line  of  Orient  the  New  Limerick  branch  unites 
v/ith  this  sei'ies  to  form  quite  a  large  and  broad  ridge,  which  is  continuous 
till  it  extends  as  a  long  sloping  point  out  into  the  north  end  of  Grand 
(St.  Croix)  Lake.  The  Calais-Houlton  road  is  built  for  several  miles  on 
the  top  of  this  ridge.  Excavations  show  miTch  sand  and  gravel,  with  some 
coarser  matter,  rounded  cobbles,  bowlderets,  and  even  a  few  water-polished 
bowlders.  In  several  places  the  lines  of  stratification  were  observed  to  dip 
quite  steeply  toward  the  south.  According:  to  the  testimony  of  numerous 
lumbermen  and  others,  a  two-sided  ridge  of  gravel  extends  for  long  distances 
on  the  bottom  of  Grand  Lake.  In  warping  rafts  of  logs  down  the  lake,  the 
lumbermen  are  liable  to  drop  anchor  in  the  yielding  gravel;  they  are  then 
obliged  to  take  up  the  anchor  and  drop  it  in  the  deejjer  water  on  each  side 
of  the  ridge,  where  they  report  finding-  a  firm  "clay  bottom."  It  is  uncei'- 
tain  whether  this  is  sedimentary  clay  or  till.  The  osar  appears  on  the  land 
at  several  of  the  capes  of  Grand  Lake,  and  disappears  beneath  the  water 
while  crossing  the  intervening  bays.  Thus  at  Birch  Point,  Weston,  the 
osar  runs  out  as  a  long  bar  for  a  considerable  distance  into  the  lake;  and, 
according  to  report,  the  small  islands,  "Billy  and  Ann,"  are  composed  of 
rounded  gravel.  If  so,  they  are  parts  of  the  osar  which  rise  above  the  lake. 
The  outlet  of  Grand  Lake  is  from  the  eastern  side,  about  5  miles  from 
the  south  end  of  the  lake.  The  portion  of  the  lake  south  of  the  outlet  is 
called  the  "Arm  of  Grand  Lake,"  and  is  inclosed  between  two  north-and- 
south  ranges  of  hills.  Going  south  we  find  these  hills  ap^Droaching  each 
other,  so  that  at  the  south  end  of  the  arm  they  are  separated  by  a  narrow 
V-shaped  valley,  whose  sides  rise  steeply  upward  several  hundred  feet. 
One  of  these  hills  is  called  Spruce  Mountain.  The  osar  gravel  is  found  for 
several  miles  along  the  west  side  of  the  Arm  of  the  Lake.  At  the  south 
end  of  the  lake  it  forms  a  distinct  two-sided  ridge,  which  has  been  exca- 
vated for  road  gravel.  It  is  thus  revealed  that  near  the  axis  of  the  ridge 
finely  stratified  sand  and  gravel  dips  21  degrees  in  a  nearly  south  direction, 


76  GLACIAL  GEAVELS  OF  MAINE. 

aud  this  over  an  exposure  40  feet  long  and  6  feet  high.  A  small  brook 
flows  uortlnvard  into  the  lake  at  this  point,  but  it  is  only  about  1  mile  in 
length,  and  could  never  cany  much  sediment  into  the  lake ;  still  less  could 
it  give  its  sediments  a  southward  dip.  The  gravel  on  the  beach  of  the 
lake,  as  well  as  the  small  amount  of  gravel  brought  down  by  this  brook, 
has  very  nearly  the  till  shape,  and  is  nowhere  well  rounded  like  the  gravel 
of  the  two-sided  ridge  at  the  foot  of  the  lake.  It  thus  becomes  evident 
that  this  ridge  is  the  osar.  A  short  distance  south  of  the  foot  of  the  lake 
the  ridge  becomes  low,  and  the  stratified  sand  and  gravel  are  almost 
covered  from  sight  by  a  pellmell  mass  resembling  a  stony  till  containing 
numerous  till  bowlders.  But  for  road  excavations  one  would  hardlv  sus- 
pect the  existence  of  this  hidden  gravel. 

This  till-like  mass  might  be  accounted  for  in  several  ways.  (1)  It 
might  be  due  to  a  landslide;  but  I  could  discover  no  place  bare  of  till,  or 
any  other  sign   of  a  landslip,  at  least  on  the  lower  slopes  of  the  hills. 

(2)  It  might  be  due  to  ice  floes  stranded  at  a  time  when  the  lake  stood 
about  10  or  15  feet  higher  than  at  present.  Nowhere  else  on  the  shore  of 
the  lake  did  I  discover  such  proofs  of  the  water  having  stood  at  a  higher 
level.  It  must  be  admitted,  however,  that  the  shape  of  the  Arm  of  the 
Lake  is  very  well  adapted  to  cause  a  convergence  of  floes  to  this  place. 

(3)  The  till  may  have  tumbled  down  upon  the  sediment  of  the  glacial 
stream,  either  into  a  subglacial  tunnel  or  from  the  sides  into  a  suj^erflcial 
channel. 

My  brief  visit  did  not  permit  me  to  explore  the  shore  of  the  lake  very 
far.  The  gravel  ridge  becomes  less  conspicuous  as  we  go  southward  from 
the  lake,  and  disappears  within  three-fourths  of  a  mile,  at  an  elevation  of 
not  more  than  30  feet  above  the  lake.  The  ground  continues  to  rise  very 
gently  for  somewhat  more  than  a  inile,  and  then  slopes  southward  down  the 
■  valley  of  the  east  branch  of  the  Tomah  Stream.  The  highest  part  of  this 
divide  is  hardly  more  than  50  feet  higher  than  the  lake.  It  is  certain  that 
an  osar  stream  flowed  southward  from  the  Arm  of  Grand  Lake  through 
this  very  low  pass,  where  it  was  for  2  miles  or  more  hemmed  in  by  high 
hills  on  each  side.  But  the  gravel  is  rather  fine  and  the  ridge  is  not  large. 
This  indicates  a  stream  of  moderate  velocity  and  size.  The  course  of  this 
stream  must  have  been  somewhere  to  the  south  or  southeast.  Its  most 
natural  route  lay  down  the  valley  of  the  east  branch  of  Tomah  Stream, 


HOULTON-DENNTSVILLE  SYSTEM.  77 

which  crosses  the  Maine  Central  Raih'oad  a  short  distance  east  of  Tomah 
station,  but  for  5  or  more  miles  I  have  no  note  of  any  g-lacial  gravels.  The 
country  is  a  wilderness  difficult  to  traverse,  and  even  large  ridges  might 
easily  escape  observation.  The  difficulty  of  the  search  is  increased  by  the 
fact  that  near  the  lake  the  gravel  is  covered  by  considerable  till,  and  this 
condition  may  continue  for  some  miles  southward.  And  if  the  ridge  is  not 
large  at  the  south  end  of  the  Arm  of  the  Lake,  on  an  iip  slope,  it  should  be 
expected  that  on  a  southward  or  down  slope  of  15  or  more  feet  per  mile 
the  stream  would  sweep  its  channel  clear  of  all  except  the  coarsest  matter. 
It  is  thus  seen  that  although  glacial  gravels  could  not  be  found  for  a  con- 
siderable distance,  this  fact  does  not,  under  the  circumstances,  prove  that 
the  glacial  stream  did  not  flow  down  this  valley.  Careful  search  and  inquiry 
failed  to  show  any  line  of  gravels  reaching  from  the  foot  of  Grand  Lake  to 
Lambert  Lake  or  other  point  southwestward. 

A  mile  or  two  south  of  Tomah  station  the  two  branches  of  Tomah 
Stream  unite,  and  from  this  point  of  junction  an  extensive  series  of  reticu- 
lated ridges  and  broad  plains  of  sand  and  gravel  are  found  in  the  valley  of 
the  main  stream,  extending  to  near  the  mouth  of  Little  Tomah  Stream  in 
Codyville.  These  large  plains  demand  the  assumption  of  large  glacial 
streams.  The  Smyrna-Danforth  osar  river  flowed  down  the  valley  of  the 
west  branch  of  Tomah  Stream.  This  was  a  larger  glacial  river  than  that 
which  flowed  south  from  Grand  Lake,  and  while  it  was  competent  to  have 
brought  down  the  large  plains  of  the  Tomah  Valley,  yet  the  probable  his- 
tory of  these  plains  is  as  follows:  The  two  glacial  rivers,  one  from  the 
direction  of  Houlton  and  Grand  Lake,  the  other  from  Danforth,  united 
near  where  the  two  branches  of  Tomah  Stream  now  unite,  and  together 
produced  the  sand  and  gravel  plains  extending  into  Codyville.  The  eleva- 
tion of  Toixiah  station  is  370  feet,  and  I  estimate  the  elevation  of  the  plains 
north  of  Codyville  to  be  more  than  200  feet.  The  southern  part  of  these 
plains  may  therefore  be  a  marine  delta. 

From  near  the  mouth  of  Little  Tomah  Stream  the  ridge  varies  from  10 
to  25  feet  in  height.  Its  lateral  slopes  are  gentle,  thus  making  it  quite 
broad  for  its  height.  The  ridge  crosses  the  Schoodic  River  at  an  elevation 
of  165  feet,  and  continues  southward  near  the  line  between  Bailey ville  and 
Princeton.  In  the  southern  part  of  Baileyville  and  in  Alexander  the  sys- 
tem becomes  broken  by  several  gaps  while  following  a  rather  low  pass. 


78  GLACIAL  GRAVELS  OF  MAINE. 

and  runs  into   the   nortli  end   of   Meddybemps  Lake  at   an   elevation   of 
150  feet.i 

The  southwestern  ang-le  of  the  broad  part  of  this  lake  is  bordered  by 
a  large  peat-covered  heath,  in  the  midst  of  which  is  a  rounded  hummock, 
said  to  be  composed  of  sand  and  gravel.  It  rises  about  30  feet  above  the 
peat  and  is  in  the  line  of  the  gravels;  it  is  probably  a  part  of  the  system. 
From  near  the  south  end  of  this  heath  a  plain  of  sand  and  gravel  extends 
southward  along  the  eastern  base  of  a  hill  which  lies  parallel  with  the  lake 
and  outlet,  and  about  1  mile  west  of  them.  On  the  north  this  plain  shows 
mounds  and  low  ridges  of  gravel  rising  above  the  surrounding  plains  of 
gravel.  It  is  here  less  than  one-fourth  of  a  mile  in  breadth.  Going  south- 
ward the  material  becomes  finer,  the  top  is  more  level,  and  it  expands  laterally, 
so  as  to  be  neaidy  a  mile  broad  at  the  point  where  it  is  crossed  by  the  road 
leading  west  from  Meddybemps  Post-Office.  Both  the  east  and  west  sides 
of  the  plain  here  rise  steeply  above  the  sedimentary  clay  and  sandy  clay 
which  flank  it,  as  a  narrow  border,  toward  the  north  at  the  angde  of  the  lake, 
but  toward  the  south  it  becomes  broader,  so  as  to  cover  the  whole  valley 
not  far  south  of  Meddybemjjs  Village.  Near  there  the  gravel  plain  becomes 
finer  by  degrees  and  rises  not  so  far  above  the  clay,  and  soon  they  merge 
into  each  other  and  extend  as  a  sheet  of  marine  clay  all  the  way  to  the  sea. 
The  ]jlain  lying  west  of  the  ^-illage  is  thus  seen  to  have  the  gradatioiis  of 
sediments  characteristic  of  the  delta  when  examined  leng-thwise.  Why, 
then,  did  it  not  spread  outward  across  the  whole  valley?  From  the  village 
northward  the  gravel  plain  lies  about  40  feet  above  the  outlet  of  the  lake 
and  the  river.  Had  the  ice  melted  over  the  whole  valley,  the  gravel  plain 
and  its  bordering-  clay  would  have  spread  across  the  valley  and  along  the 
shores  of  the  lake,  whereas  no  clay  to  speak  of  appears  at  the  lake.  This 
can  be  accounted  for  only  on  the  hypothesis  that  at  the  time  the  g-ravel  plain 
west  of  the  village  was  being  deposited  ice  still  covered  the  locality  now 
occupied  by  the  eastern  part  of  the  lake  and  the  valley  of  Dennys  River 
and  as  far  south  as  where  the  g'ravel  and  sand  delta  merge  into  the  marine 
clay.  Here  was  the  ice  front,  and  to  the  south  lay  the  open  sea,  where  the 
finer  sediments  were  spread  far  and  wide.  To  the  north  lay  a  broad  chan- 
nel in  the  ice.     The  elevation  of  the  place  where  the  sea  margin  then  stood  was 

'This  lake  is  estimated  at  250  feet  in  Walter  Wells's  Water  Power  of  Maine,  p.  129,  Augusta, 
1869.  This  was  a  typographical  error.  The  estimate  sent  to  Mr.  Wells  hy  P.  E.  Vose,  esq.,  of 
Dennysville,  was  150  feet. 


HOULTON-DENISTSVILLE  SYSTEM.  79 

140  to  150  feet.  The  elevation  of  the  sea  was  certainly  as  much  as  this,  and 
it  may  have  stood  higher,  possibly  up  to  its  highest  level,  about  225  feet. 

The  local  history  Avas  probably  about  as  follows:  The  original  narrow 
osar  channel  in  the  ice  became  broadened,  and  in  this  broad  channel  the 
gravel-and-sand  delta  was  deposited.  The  channel  broadened  recessively 
northward,  and  thus  the  time  came  when  the  coarser  sediments  brought  from 
the  north  were  deposited  at  points  considerably  north  of  Meddybemps  Vil- 
lage, perhaps  as  far  as  the  north  end  of  the  lake  or  in  the  lake.  The  finer 
sediments  were  at  this  time  brought  down  farther,  and  formed  the  clays 
bordering  the  sand  plain  opposite  the  village  and  southward.  The  time 
must  have  come  when  the  ice  all  melted  over  the  valley  where  the  lake  now 
is,  but  by  this  time  the  sea  had  advanced  up  the  valleys  of  the  St.  Croix, 
the  Schoodic,  and  the  Tomah,  so  that  this  great  glacial  river  poured  into 
the  sea  near  Codyville,  many  miles  northward.  The  supply  of  sediment 
was  thus  cut  off  from  the  north,  so  that  when  the  open  sea  at  last  prevailed 
over  all  the  upper  valley  of  Dennys  River  and  Meddybemps  Lake,  but 
very  little  clay  was  deposited,  except  where  the  old  river  channel  had  been. 

If,  during  any  of  the  time  the  delta  west  of  the  village  was  being 
formed,  the  sea  stood  above  the  level  of  about  140  to  150  feet,  the  channel 
of  the  glacial  river  was  in  fact  a  bay  within  the  ice,  where  the  sea  met  the 
fresh  water.  During  the  time  of  the  summer  flood  of  the  glacial  river  the 
muddy  fresh  water  would  fill  all  this  broad  channel  or  bay,  but  in  winter, 
when  the  glacial  waters  were  scanty,  it  would  be  a  sort  of  estuary  inclosed 
between  walls  of  ice.  As  the  high  tides  of  that  region  prevailed,  the  salt 
water  would  naturally  extend  for  some  distance  up  the  g-lacial  channel,  just 
as  it  does  up  the  rivers  of  to-day.  (This  and  all  other  descriptions  should 
be  read  with  the  map  in  hand.) 

Southward  from  Meddybemps  the  series  extends  along  the  west  side 
of  Deiinys  River,  through  Dennysville,  and  for  a  short  distance  into 
Edmunds.  It  is  discontinuous  all  the  way,  and  becomes  more  so  toward  the 
south,  until  in  Edmunds  the  ridges  are  onl}^  one-third  of  a  mile  or  less 
in  length  and  not  more  than  one-eighth  of  a  mile  in  breadth. 

In  the  southern  part  of  Edmunds  and  in  Trescott  are  numerous  gravel 
beds,  which  are  found  on  the  slopes  of  hills  having  a  southward  or  eastward 
exposure.     I  formerly   supposed   them    to   be    connections  of  this   gravel 


80  GLACIAL  GRAVELS  OF  MAINE. 

system,  but  I  have  since  examined  several  whicli  proved  to  be  beach  gravel. 
I  therefore  provisionally  mark  the  end  of  this  system  in  the  northern  part 
of  Edmunds.     Length  from  Edmunds  to  T.  9,  R.  4,  115  miles.^ 

NEW   LIMERICK-AMITT    BRANCH. 

This  branch  extends  from  near  the  center  of  the  town  of  New  Lim- 
erick through  Linneus,  Car}'^  Plantation,  and  Amity,  and  joins  the  Houlton 
branch  near  the  north  line  of  Orient.  Toward  the  north  this  osar  is  quite 
continuous  and  prominent,  with  conspicuous  meanderings.  Southward  it  is 
somewhat  interrupted  by  short  gaps.  It  traverses  a  rolling  plain,  and  sev- 
eral times  passes  from  one  valley  to  another  over  a  low  divide.  South  of 
where  this  and  the  Houlton  branch  unite,  the  ridge  is  larger  and  more  con- 
tinuous than  is  either  branch  for  several  miles  north  of  their  junction.  The 
average  size  of  this  branch  is  about  as  large  as  the  Houlton  branch,  though 
it  does  not  expand  to  so  great  size  as  the  latter  at  Carys  Mills.  Length, 
about  20  miles. 

SMYRNA-DANPORTH    BRANCH. 

Measured  by  the  amount  of  gravel  which  the  Smyrna-Danforth  glacial 
river  deposited,  it  deserves  to  be  classed  as  the  main  tributary  and  the 
Houlton  Eiver  as  a  branch.  According  to  this  nomenclature,  the  system 
ought  to  be  known  as  the  Smyrna-Demaysville  system.  But,  on  the  whole, 
there  are  such  advantages  in  considering  the  longer  tributary  as  the  main 
river  that  the  Houlton  branch  has  been  considered  the  main  one,  although 
it  is  by  no  means  certain  that  a  careful  exploration  will  not  sliow  the 
Smyrna  branch  to  be  longer  than  that  which  passes  near  Houlton. 

The  other  connections  of  the  Smyrna  series  are  uncertain.  A  ridge  of 
gravel,  probably  glacial,  is  reported  as  being  found  a  short  distance  south 
of  St.  Croix  Lake.  The  divide  between  the  Masardis  River,  flowing  north- 
ward, and  the  east  branch  of  the  Mattawamkeag  is  so  level  that  the  waters 
of  one  stream  have  been  diverted  into  the  other  by  a  ditch.  The  valleys 
of  these  two  streams  thus  form  a  continuous  valley  with  slopes  favorable 
for  a  long  osar  system  to  extend  from  the  vicinity  of  Masardis  south  and 
eastward  to  Sm5a-na.  I  crossed  the  Masardis  River  in  the  No.  9  townships 
and  explored  its  valley  for  several  miles,  but  no  gravels  were  found  near 


'I  am  indebted  to  Mr.  John  C.  Carpenter,  of  Houlton,  for  much  valuable  information  relating 
to  the  gravels  of  Aroostook  County. 


SMYENA-DANFORTH  BRANCH.  81 

the  river.  The  forest  is  so  dense,  however,  that  one  could  easily  miss  a 
gravel  system  unless  following  it  lengthwise.  In  T.  9,  R.  5,  several  short 
ridges  of  true  glacial  gravel  are  found  a  few  miles  Avest  of  the  Masardis 
River,  and  it  is  not  impossible  that  they  are  part  of  a  series  extending  past 
St.  Croix  Lake  to  Smyrna. 

From  near  Smyrna  Mills  the  gravel  series  takes  the  form  of  a  nearly 
continuous  and  rather  flat-topped  plain  of  sand  and  gravel  following  the 
east  branch  of  the  Mattawamkeag  to  Haynesville.  In  places  the  plain, 
before  being  eroded  by  the  stream,  extended  across  the  whole  of  the  rather 
nan'ow  valley.  The  river  sometimes  flows  at  one  side  of  the  gravel  plain, 
but  more  often  it  has  eroded  the  central  part,  thus  being  bordered  on  each 
side  by  terraces  of  erosion.  Sometimes  it  has  cut  out  two  channels,  leav- 
ing a  central  ridge  uneroded.  It  will  thus  be  seen  that  the  alluvium  con- 
tained in  the  narrower  parts  of  the  valley  presents  the  external  features  of 
ordinary  valley  drift.  The  material  of  this  alluvial  plain  is  in  general 
composed  of  sand  and  fine  gravel,  but  with  a  mixture  of  larger  pebbles, 
cobbles,  and  some  bowlderets.  The  stones  ai'e  much  rounder  than  those 
found  in  the  beds  of  the  other  streams  of  this  region,  and  must  have  been 
subjected  to  much  greater  attrition.  In  some  places  the  valley  broadens 
considerably.  Here  the  gravel  plain  does  not  widen  correspondingly,  so 
as  to  fill  the  whole  valley,  but  sometimes  is  bordered  on  the  side  away  from 
the  river  by  a  steejJ  bank  downward,  which,  so  far  as  I  could  determine,  is 
not  due  to  erosion.  The  alluvial  plain  of  highly  rounded  matter  is  thus 
shown  to  be  of  glacial  origin,  and  not  a  plain  of  ordinary  river  drift.  Its 
breadth  varies  from  a  few  rods  to  about  one-fourth  of  a  mile.  This  plain 
is  a  good  instance  of  what  I  have  elsewhere  named  the  osar-plain,  or  broad 
osar. 

Not  far  north  of  Haynesville  this  series  is  joined  by  another  series, 
from  Island  Falls.  At  Haynesville  the  gravel  forms  a  single  plain  about 
one-eighth  of  a  mile  broad,  which  shows  that  the  two  tributary  glacial 
rivers  here  flowed  as  one.  The  two  branches  of  the  Mattawamkeag  River 
also  unite  not  far  north  of  Haynesville  to  form  the  main  river.  The  river 
here  flows  in  a  broad  and  quite  level  valley.  For  4  miles  southeast  of 
Haynesville  an  osar-plain  of  sand  and  gravel  extends  along  the  axis  of  the 
valley,  bordered  by  a  plain  of  horizontally  stratified  sand  and  silt,  one-half 
mile  or  more  wide.  In  many  places  this  sand  has  blown  into  low  dunes. 
MON  xxxiv 6 


82  .  GLACIAL  GEAVELS  OF  MAINE. 

Excavations  not  iu  the  dunes  show  the  sand  overlying  the  till  and  till 
bowlders.  This  bordering  sand  plain  has  the  external  features  of  valley 
drift.  At  the  great  bend,  or  "oxbow,"  of  the  Mattawamkeag  the  river 
makes  an  abrupt  turn  from  a  southeast  to  a  southwest  course.  The  osar- 
jDlain  here  leaves  the  river  valley  and  goes  on  southward  through  Weston 
to  Danforth.  The  character  of  the  alluvium  of  the  Mattawamkeag  Valley 
here  changes.  Below  this  point  the  river  shows  an  alternation  of  long 
reaches  of  dead  water  separated  by  short  rapids  or  falls.  Along  the  level 
parts  of  the  valley  the  river  drift  consists  of  clay  and  silt,  with  sand,  sub- 
angular  coarse  gravel,  and  even  bowlderets  and  bowlders  at  the  rapids. 
The  rapids  are  found  at  places  where  the  ice-sheet  left  deep  masses  of  till 
spread  across  the  valley.  The  only  gravel  found  in  the  valley  below  the 
oxbow  is  the  result  of  the  river's  eroding  the  till,  and  the  shapes  of  the 
stones  are  very  different  from  those  of  the  osar-plain  in  Haynesville. 
True,  some  rounded  stones  can  be  found  in  the  bed  of  the  river,  or  as  a 
part  of  the  loAvest  terrace,  for  some  miles  below  the  oxbow,  but  they  were 
probably  washed  down  from  the  osar-plain,  although  I  could  not  prove  them 
to  be  contemporaneous  with  it  or  with  auj-  of  the  higher  terraces.  The  till 
ridges  left  across  the  valley  of  the  Mattawamkeag  must  originally  have 
caused  a  series  of  lakes  to  form  in  the  valley  directl)^  after  the  melting  of 
the  ice.  The  broad  sand  plain  found  bordering  the  osar-plain  proper  in 
Hapiesville  might  thus  be  a  lake  delta  if  a  till  barrier  high  enough  to  form 
a  lake  at  that  level  existed.  Thus  far  I  have  found  no  barrier  high  enoiTgh 
for  the  purpose.  Concerning  the  broad  plains  of  the  Mattawamkeag 
Valley  extending  from  Haynesville  to  the  oxbow,  it  is  safe  to  conclude, 
first,  that  the  sand-and-gravel  plain  near  the  center  of  the  valley  is  a  true 
osar-plain;  second,  that  the  bordering  plain  of  sand  was  probably  deposited 
in  a  still  broader  channel  Avithin  the  ice,  making  it  in  fact  a  glacial  lake; 
yet  there  is  nothing  in  its  form  to  disprove  the  hypothesis  that  it  was  formed 
in  an  ordinary  lake  if  a  till  barrier  (now  cut  through  by  the  river)  of  suffi- 
cient height  can  be  found;  or  it  may  possibly  be  an  overwash  or  frontal 
plain  deposited  when  the  ice  had  retreated  a  little  north  of  Haynesville. 

A  plain  of  sand  and  fine  gravel  extends  from  the  great  bend  of  the . 
Mattawamkeag  southward  through  Weston.     It  is  one-eighth  of  a  mile  or 
more  wide,  and  ascends  the  valley  of  a  small  brook  which  flows  northward. 
The  stream  has  excavated  numerous  terraces  of  erosion  in  the  osar-plain. 


SMYENA-DANFOETH  BEANCH.  83 

The  plain  is  quite  continuous  on  the  northern  slope  until  it  reaches  a  height 
of  75  or  100  feet  above  the  Mattawamkeag-  River.  It  then  is  somewhat 
discontinuous  while  passing  over  a  divide,  and  then  it  takes  the  form  of  an 
osar-ridge  from  15  to  40  feet  high,  containing  much  coarse  matter,  very 
round  cobbles,  and  some  bowlderets.  The  ridge  continues  southward  for 
several  miles,  and  then,  making  a  beautiful  curve  to  the  left,  it  turns  south- 
eastward and  crosses  the  Baskahegan  Stream  about  1  mile  north  from  Dan- 
forth  Village.  It  follows  the  western  bank  of  this  stream  through  Danforth 
Village,  and  then,  leaving  the  Baskahegan  Valley,  which  lay  directly 
before  it,  it  turns  more  to  the  eastward  along  the  valley  of  Crooked  Brook. 
It  goes  up  this  valley  and  over  a  divide  near  Forest  station,  and  thence 
follows  the  valley  of  the  west  branch  of  Tomah  Stream  to  its  jimction 
with  the  Hotilton  osar,  not  far  south  of  Tomah  station.  Between  Danforth 
and  Tomah  stations  of  the  Maine  Central  Railroad,  this  great  gravel  system 
follows  the  same  valley  or  pass  as  that  followed  by  the  railway.  About 
one-fourth  of  a  mile  northeast  of  Danforth  Village  there  is  a  small  hillside 
kame  at  nearly  right  angles  to  the  main  osar.  It  slopes  rather  steeply  down 
a  hill  for  nearly  one-eighth  of  a  mile  and  disappears.  It  was  evidently 
deposited  by  a  small  lateral  tributary  of  the  main  glacial  river.  The  gravel 
comes  to  an  end  within  one-fourth  of  a  mile  from  the  main  osar.  Near 
Danforth  the  gravel  is  fine  enoiigh  to  serve  as  railroad  ballast.  Going 
eastward  up  the  slope,  we  find  the  material  becoming  coarser,  and  at  the 
top  of  the  divide  at  Forest  station  the  ridge  consists  almost  wholly  of  large 
pebbles,  cobbles,  ■  and  bowlderets.  East  of  this  point  the  valley  of  the 
west  branch  of  the  Tomah  Stream  has  a  fall  of  about  30  feet  per  mile 
southeastward,  and  for  about  3  miles  east  of  the  col  the  gravels  are  very 
scanty  and  difficult  to  trace.  Apparently  on  this  steep  down  slope  the  force 
of  the  glacial  river  was  such  as  to  sweep  before  it  all  but  the  larger 
bowlderets  and  bowlders.  The  valley  is  one  of  the  dreariest  bowlder  fields 
in  the  State.  The  rounded  gravel  becomes  easily  traceable  at  a  point 
about  west  of  Tomah  station,  and  so  continues  down  the  valley,  soon 
expanding  into  the  plains  north  of  Codyville,  as  before  described.  To  these 
plains  this  tributary  probably  contributed  much  more  material  than  the 
Houlton  branch. 

The  most  noteworthy  features  of  this  important  gravel  series  are  the 
following :  For  a  considerable  part  of  its  course  it  takes  the  form  of  a  plain 


84  GLACIAL  GRAVELS  OF  MAOE, 

with  rather  level  top  in  the  cross  section.  When  traversing-  narrow  valleys, 
this  plain  appears  like  valley  drift,  hut  is  distinguishable  from  it  by  the 
very  round  shape  of  the  pebbles,  by  its  greater  size  than  the  valley  drift  of 
the  region,  by  the  larger  size  of  its  stones,  by  the  fact  that  it  does  not 
always  spread  laterally  to  fill  the  valleys  in  which  it  is  situated,  and,  still 
more  conclusively,  by  its  going  up  and  over  hills.  While  crossing  the 
lower  ground  the  material  is  rather  fine,  approaching  the  top  of  hills  it 
becomes  coarser,  and  on  a  steep  down  slope  it  is  scanty  or  absent  for  a  mile 
or  more.  In  Haynesville  the  osar-plain  proper  is  flanked  by  sand  plains. 
Apparently  the  osar  was  first  deposited  in  a  channel  one-eighth  to  one- 
fourth  of  a  mile  wide.  This  was  situated  north  of  a  hill  75  or  100  feet 
high,  and  the  water  must  have  been  at  least  of  that  depth  in  order  to  flow 
southward  over  the  hill.  Subsequently  this  chamiel  was  widened  by  lateral 
melting  of  the  ice,  until  it  became  one-half  mile  or  more  wide  and  approxi- 
mated the  condition  of  a  lake  75  or  more  feet  deep.  In  this  a  plain  of 
fine  sand  was  deposited  at  the  flanks  of  the  central  plain  of  gravel.  This 
plain  has  subsequently  been  somewhat  modified  by  the  winds  and  by  the 
floods  of  the  Mattawamkeag  River,  and  to  that  extent  is  valley  drift.  No 
30  miles  of  any  other  osar  of  eastern  Maine  at  such  a  distance  from  the 
coast  has  so  great  a  cubic  content  as  this  series  for  the  30  miles  north  of 
Danforth. 

Length,  about  45  miles. 

ISLAND   FALLS   BRANCH. 

A  nearly  continuous  osar  extends  from  Merrill  Plantation  southward 
near  the  line  between  Dyer  Brook  and  Hersey  to  the  village  of  Island 
Falls,  and  thence  southeastward  along  the  western  shore  of  Mattawamkeag 
Lake  and  the  west  branch  of  the  Mattawamkeag  River,  and  joins  the 
Smyrna  branch  a  short  distance  north  of  Haynesville.  In  some  places, 
especially  toward  the  south,  the  gravel  widens  so  as  to  approach  the  form 
of  the  flat-topped  osar-plain,  but  for  most  of  the  distance  it  takes  the  form 
of  a  two-sided  ridge  with  arched  cross  section. 

Since  the  Smyrna  and  the  Island  Falls  tributaries  are  near  each  other 
and  are  at  equal  distances  from  the  sea,  and  penetrate  regions  having  similar 
rocks  and  topography,  they  throw  light  on  each  other's  origin.  The  pebbles 
are  no  rounder  in  the  osar  than  in  the  osar-plain.      The  stones  in  both  are 


MAEIOK  AND  EAST  MACHIAS.  85 

largely  made  up  of  granite,  slates,  and  the  harder  sedimentary  rocks,  and 
in  both  are  much  rounder  than  the  stones  of  the  streams  of  this  region  not 
in  the  lines  here  indicated  for  the  glacial  gravels.  These  points  had  to  be 
carefully  studied  before  it  became  evident  that  the  plain  of  rounded  gravel 
situated  in  the  valley  of  the  east  branch  of  the  Mattawamkeag  between 
Smyrna  and  Haynesville,  where  the  slope  of  the  river  coincided  with  that 
of  the  glacial  stream,  was  really  an  osar-plain  and  not  ordinary  valley  drift. 

LOCAL   KAMES    IN    MARION. 

A  short  kame  is  situated  on  the  east  side  of  Rocky  Brook  in  the 
northern  part  of  Marion.  Another  is  found  near  the  southeast  angle  of 
the  northern  division  of  Gardners  Lake.  It  is  a  narrow  ridge  rising  15  to 
20  feet  above  the  marine  clay,  and  is  about  half  a  mile  long  from  east  to 
west.  It  has  the  direction  of  a  terminal  moraine,  but  appears  to  consist 
wholly  of  water-washed  gravel. 

On  the  western  side  of  the  long  point  of  land  Avhich  projects  from  the 
eastern  shore  of  Gardners  Lake,  so  far  as  almost  to  divide  the  lake  into  two 
separate  lakes,  is  a  broad  ridge  or  plain  of  rounded  gravel  and  cobbles.  It 
has  been  eroded  by  the  waves  on  its  western  side  so  as  to  form  a  prominent 
beach  cliff. 

These  gravel  deposits  of  Marion  do  not  appear  to  have  been  formed 
by  asingle  glacial  stream,  and  therefore  they  are  not  classed  as  a  system. 
There  are  many  old  beaches  in  Marion  on  hills  that  would  he  exposed  to 
the  surf  while  the  sea  stood  at  higher  level  than  now. 

EAST    MACHIAS    SYSTEM. 

This  system  begins  abruptly  in  T.  18  near  where  the  road  from  East 
Machias  to  Crawford  is  intersected  by  the  road  leading  west  from  Dennys- 
ville.  The  gravel  here  takes  the  form  of  a  single  two-sided  ridge  10  to  30 
feet  high.  Going  southward  we  here  and  there  find  two  or  more  ridges 
inclosing  kettleholes,  and  then  the  gravel  soon  becomes  discontinuous. 
Still  farther  south  the  gaps  become  longer  and  the  gravel  ridges  shorter, 
until  the  system  ends  as  a  series  of  small  rounded  hummocks  or  cones, 
separated  b}'  intervals  of  from  one-eighth  to  one-half  a  mile.  The  last  of 
the  gravel  hillocks  which  I  could  find  was  a  short  distance  south  of  East 
Machias  Village.  South  of  this  point  were  a  low  pass  and  a  plain  covered 
by  marine  clay.     Although  the  system  ends  several  miles  north  of  the  open 


86  GLACIAL  GRAVELS  OF  MAINE. 

sea,  yet  the  end  is  only  a  few  feet  above  tide  water.  Toward  the  north  the 
ridges  of  this  system  are  broad  and  massive,  with  gentle  side  slopes.  The 
stones  are  well  rounded  throtighout  the  whole  length  of  the  system,  and 
among  them  are  a  multitude  of  bowlderets  and  bowlders,  up  to  3  feet  in 
diameter.  It  lies  on  a  southern  slope  favorable  to  the  flow  of  the  water 
until  the  ice  was  nearly  all  melted.  Its  course  is  quite  free  from  meanders. 
The  elevation  of  the  northern  end  is  not  precisely  known,  but  the  glacial 
stream,  at  the  time  the  sea  stood  at  230  feet,  would  flow  into  it  not  far  from 
the  north  end  of  the  system.  This  is  where  the  broad,  almost  plain-like, 
ridges,  inclosing  kettleholes,  are  found.  The  large  size  of  the  bowlders 
in  this  system  makes  it  quite  probable  that  this  was  the  work  of  a  subglacial 
river. 

Length,  about  10  miles. 

CRAWFORD   SYSTEM. 

A  short  deposit  of  glacial  gravel  is  found  about  2  miles  north  of  Craw- 
ford Church,  in  a  low  valley  leading  south  from  Crawford  Lake.  This  val- 
ley contains  a  small  brook  which  flows  northward  and  has  partially  eroded 
the  kame,  though  the  brook  is  but  little  more  than  half  a  mile  long.  A 
valley  leads  over  a  low  divide  from  this  point  southward,  but  no  gravels 
have  been  found  near  the  height  of  the  pass.  Directly  in  front  of  this  pass, 
toward  the  south,  is  a  plain  of  sand  and  gravel  about  one-fourth  of  a  mile 
in  diameter.  It  is  situated  near  the  northwestern  angle  of  Love  Lake,  in 
the  southern  part  of  Crawford.  The  plain  is  rather  level  on  the  top,  and 
the  material  is  finer  toward  the  south.  It  rises  steeply  above  the  surround- 
ing till  to  a  heig'ht  of  from  6  to  15  feet.  It  thus  has  every  appearance  of  a 
delta.  Its  elevation  above  the  sea  is  probably  from  250  to  300  feet.  No 
marine  clay  appears  below  this  point,  and  I  regard  the  plain  as  having  been 
deposited  in  a  small  glacial  lake.  Near  the  southwestern  angle  of  Love 
Lake  there  is  another  and  longer  gravel  plain,  and  from  that  point  a  some- 
what discontinuous  two-sided  ridge  extends  southward  into  Ts.  19  and  20. 
It  is  for  several  miles  nearly  parallel  with  the  outlet  of  Love  Lake.  At 
the  road  from  Crawford  to  East  Machias  it  leaves  this  valley,  and  the  road 
is  made  upon  it  for  about  1  mile  south,  when  the  system  bends  southwest- 
ward.  It  is  said  to  end  in  a  level  sand-and-gravel  plain  near  the  East 
Machias  River,  not  far  south  of  Round  Lake. 


CRAWFORD  SYSTEM.  87 

The  map  shows  that  this  gravel  series  is  nearly  in  the  direction  of  the 
East  Machias  system  prolonged  northward.  Several  small  ridges  of  sub- 
angular  glacial  gravel  are  found  intermediate  between  the  two  systems. 
They  are  in  T.  18,  near  the  road  from  Crawford  to  East  Machias.  They 
are  found  on  the  western  slopes  of  the  rather  high  hills  which  border  the 
valley  of  the  East  Machias  River  on  the  east.  Theu'  course  is  westward 
down  the  hills,  and  I  regard  them  as  short  hillside  kames  deposited  by 
small  glacial  streams  which  were  either  lateral  tributaries  of  a  large  glacial 
stream  in  the  valley  or  flowed  iuto  the  sea  at  the  time  it  extended  far  north 
in  the  valley  of  the  East  Machias  River.  This  valley  is  very  inaccessible, 
and  my  exploration  was  confined  to  the  region  lying  near  the  road  from 
East  Machias  to  Crawford. 

According  to  my  present  information,  it  would  appear  that  the  glacial 
and  postglacial  history  of  the  broad  and  plain-like  valley  of  the  East 
Machias  River  is  about  as  follows: 

None  of  the  longer  glacial  rivers  flowed  through  this  valley,  the  di-ain- 
age  of  the  glacier  to  the  north  being  either  carried  off  eastward  by  the 
Dennysville  system  or  westward  down  the  valley  of  the  Machias  River. 
The  East  Machias  system  of  glacial  gravels  was  wholly  deposited  before 
the  melting  of  the  ice,  unless  the  enlargement  of  the  system  before  described 
as  being  found  about  2  miles  from  its  northern  extremity  prove  to  be  a 
marine  delta.  At  the  time  the  ocean  stood  at  the  contour  of  225  feet,  an 
arm  of  the  sea  3  to  5  miles  broad  extended  northward  up  this  valley  to 
Crawford,  and  probably  was  continuous  with  the  bay  of  salt  water  which 
at  that  time  extended  up  the  valleys  of  the  St.  Croix  and  Schoodic  rivers 
to  Princeton.  The  Crawford-Love  Lake  system  was  deposited  later  than 
the  East  Machias  system,  at  a  time  when  the  ice  had  receded  so  far  north- 
ward that  all  the  valley  from  Round  Lake  southward  was  covered  by  the 
sea.  Occasional  gravel  deposits  have  been  reported  in  the  valley  near  the 
river,  but  the  descriptions  make  it  uncertain  whether  they  are  glacial  gravel 
or  till.  A  ridge  of  true  glacial  gravel  crosses  the  Air  Line  road  from  Calais 
to  Bangor  in  the  southwestern  part  of  Crawford.  It  is  near  the  East 
Machias  River,  and  is  about  a  mile  long.  Another  short  and  rather  broad 
ridge  is  found  not  far  to  the  soiith  of  it.  This  series  ought  to  end  at  the 
south  in  a  delta,  but  I  have  not  been  able  to  find  one,  unless  it  be  the 
shorter  ridge  just  mentioned.     This  short  series  is  evidently  an  incident  in 


88  GLACIAL  GRAVELS  OF  MAINE. 

the  retreat  of  the  ice  northward,  and  the  glacial  stream  which  deposited  it 
was  soon  terminated  by  flowing  into  the  sea. 

WILDERNESS     REGION     NORTH     OF    COLUMBIA,    COLUMBIA    FALLS,    AND 

JONESBORO. 

We  now  approach  a  region  very  difficnlt  to  investigate.  The  gravel 
deposits  situated  in  it  are  vast,  being  equaled  only  by  the  great  plains  of 
the  southwestern  part  of  the  State.  The  western  part  of  Washington  County 
and  the  eastern  part  of  Hancock  County  are  mostly  wooded.  There  are 
many  swamps  impassable  in  summer  or  penetrated  with  difficulty.  There 
are  only  four  continuous  east-and-west  roads  crossing  the  great  region  lying 
south  of  the  railroad  from  Mattawamkeag  to  Vanceboro.  These  roads  I 
have  traversed,  and  have  penetrated  the  wilderness  in  several  other  direc- 
tions. In  addition,  I  have  derived  much  information  from  lumbermen  and 
explorers  and  from  three  experienced  land  surveyors — Mr.  F.  I.  Campbell,  of 
Cherryfield;  Mr.  J.  R.  Buckman,  of  Columbia  Falls,  and  Mr.  H.  R  Taylor, 
of  Machias.  I  am  indebted  to  Mr.  Taylor  for  quite  an  elaborate  map  of 
this  region.  As  a  result  of  my  observations  and  inquiries,  it  is  hoped  that 
the  map  (PL  LI)  contains  all  the  larger  systems  of  glacial  gravel,  but  as  to 
the  details  of  their  courses  much  remains  to  be  done. 

The  sea  at  one  time  extended  northward  up  the  Machias  Valley  to  the 
Air  Line  road  from  Calais  to  Bangor,  in  Wesley,  and  probably  a  few  miles 
farther.  Machias  Bay  was  then  a  pretty  broad  body  of  water,  in  places  10 
or  more  miles  broad.  This  gave  great  force  to  the  waves,  and  sea  beaches 
are  found  as  far  north  as  Wesley.  The  necessity  of  distinguishing  these 
beach  gravels  from  the  glacial  gravels  in  this  wooded  country,  where  the 
whole  is  often  disguised  by  marine  clays  and  the  peats  of  swamps,  compli- 
cates considerably  the  problem  of  the  drift  of  this  valley.  The  till  is  verj^ 
heterogeneous  in  its  composition,  fragments  of  slates,  schists,  and  granite 
being  rather  indiscriminately  mixed.  The  granite  is  partly  derived  from 
local  bosses  of  that  rock  which  rise  in  the  midst  of  the  slates  and  schists, 
but  chiefly  from  the  great  area  of  granite  which  extends  from  Orland  to 
Aurora  and  thence  northeastward  past  the  region  of  the  great  Schoodic 
Lakes.  Heaps  and  trains  of  granite  bowlders  abound.  Many  of  the 
granite  stones  of  the  till  are  so  rounded  by  the  glacial  attrition  that  it  often 
requires  close  study  to  distinguish  the  till  from  a  slightly  water-washed 


WILDEENESS  REGION.  89 

glacial  gravel.  I  have  in  the  past  been  obliged  to  change  my  views  con- 
cerning some  of  these  formations,  yet,  in  spite  of  all  the  difficulties,  enough 
is  known  to  mark  the  region  as  a  very  interesting  one.  The  map  shows 
several  of  the  longer  osar  systems  of  the  State  converging  toward  an  area 
10  or  15  miles  broad  (from  east  to  west)  lying  in  Columbia,  Columbia 
Falls,  and  Jonesboro.  Over  a  very  large  area  there  is  a  convergence  of 
the  glacial  striae  toward  a  north-and-south  line  passing  through  the  same 
place.  At  several  other  places  on  the  coast  there  are  converging  strige,  but 
they  are  shown  in  small  areas  where  only  the  scratches  last  made  converge. 
It  thus  appears  that  in  these  cases  the  convergence  took  place  only  during 
the  final  retreat  of  the  ice.  But  in  the  Columbia-Jonesboro  region  all  the 
scratches  converge,  the  later  ones  more  than  the  earlier  ones.  It  is  thus 
shown  that,  like  the  Greenland  glaciers  of  to-day,  the  ice-sheet  did  not 
advance  with  an  equal  rate  of  flow  in  all  parts,  but  that  the  snow  fields  of 
the  interior  parts  of  the  State  were  discharged  more  rapidly  along  certain 
belts,  which  made  them  practically  glaciers  of  limited  breadth,  confluent, 
however-,  with  more  slowly  moving  ice.  A  stream  of  ice  about  10  miles 
wide  here  served  as  the  outlet  of  an  area  which  broadened  toward  the 
north  to  30  and  perhaps  50  miles,  and  doubtless  its  rate  of  flow  was  corre- 
spondingly rapid.  An  observer  off  the  coast  during  the  Ice  period  would 
have  seen  a  greater  number  of  icebergs  from  opposite  this  place  than  else- 
where. It  is  difficult  to  account  for  the  convergence  to  so  narrow  limits  by 
the  surface  features  of  the  land.  Tlie  area  between  the  Big  Tunk  range  of 
hills  lying  west  of  Cherryfield  and  the  hills  of  Marshfield  is  a  gently  rolling 
plain,  with  only  here  and  there  a  hill  rising  more  than  100  feet.  It  would 
be  very  natural  for  the  ice  to  be  wedged  in  between  these  ranges  of  hills,  a 
distance  of  25  miles.  Instead,  the  ice  abandoned  the  level  valley  of  the 
Narraguagus  River,  which  extends  for  15  miles  east  of  the  Big  Tunk 
Mountain,  and  crowded  eastward  toward  Columbia.  So  also  the  deflection 
westward  extended  as  far  east  as  Marion,  10  miles  east  of  the  Marshfield 
Hills.  The  central  line  toward  which  the  striae  converge  passes  near  Jones- 
boro Village,  and  the  lines  of  striation,  if  prolonged,  would  meet  at  a  point 
in  the  sea  several  miles  south  of  the  most  projecting  point  of  the  coast. 
I  have  not  been  able  to  determine  whether  there  is  any  deep  channel  of 
the  sea  south  of  Jonesboro  or  other  features  causing  this  remarkable  con- 
vergence  of  glacial  flow.      It  was    certainly  determined   by  causes  to  a 


yO  GLACIAL  GRAVELS  OF  MAINE. 

considerable  extent  independent  of  the  surface  features  of  the  present  land, 
perhaps  by  the  outline  of  the  ice  front  in  the  sea  off  the  coast. 

WESLEY-NORTHFIELD    SYSTEM. 

Wesley  Post-Office  is  situated  on  a  range  of  hills  about  200  feet  high. 
Along  the  Avestern  base  of  this  hill  is  a  rather  low  north-and-south  valley, 
in  which  lies  a  series  of  ridges  of  glacial  gravel.  The  system  may  have 
connections  northward  toward  Chain  Lake,  but  I  have  traced  it  unmistak- 
ably only  to  a  point  about  half  a  mile  southwest  of  Wesley  Post-Office. 
Beds  of  apparently  water-washed  gravel  are  found  about  2  miles  west  of 
Wesley,  but  it  is  uncertain  how  much  of  them  is  glacial  gravel  and  how 
much  is  beach  gravel.  In  view  of  the  doubt,  I  omit  them  from  the  map. 
The  series  above  described  as  beginning  near  Wesley  extends  southward  in 
a  nearly  straight  line  to  Lower  Seavey  Lake,  where  it  turns  southwestward 
and  soon  spreads  into  a  series  of  reticulated  ridges  inclosing  kettleholes. 
Going  southwestward  the  ridges  become  broader  and  the  kettleholes  more 
shallow,  and  it  soon  appears  to  be  a  marine  delta-plain.  This  series  is  said 
to  connect  with  the  Old  Stream  series  in  Centerville  and  Whitneyville. 

Length,  about  15  miles. 

TOPSFIELD-OLD    STREAM    SYSTEM. 

This  important  osar  system  appears  to  begin  not  far  north  of  Musquash 
Lake,  in  Topsfield.  At  the  road  from  Topsfield  west  to  Springfield  the 
gravel  tak-es  the  form  of  a  low  terrace  on  the  west  side  of  the  outlet  of 
the  lake.  It  consists  of  well-rounded  gravel,  and  is  distinguished  from 
valley  di'ift  partly  by  the  shape  of  the  stones  and  partly  by  appearing  on 
one  side  of  the  valley  with  no  corresponding  terrace  on  the  other  side ;  and 
often  it  takes  the  form  of  a  two-sided  ridge  while  following  the  valley  of 
Musquash  Stream.  It  is  somewhat  discontinuous,  and  for  part  of  its  course 
takes  the  form  of  an  osar-plain  that  once  extended  across  the  valley,  but  is 
now  deeply  eroded  into  terraces  by  the  stream.  The  material  is  rather  fine, 
and  the  size  of  the  deposit  is  in  general  not  very  large.  In  the  southern 
part  of  the  valley  of  Musquash  Stream  it  becomes  a  ridge  20  to  40  feet 
high,  with  moderately  steep  lateral  slopes.  For  several  miles  in  the  midst 
of  a  low  level  region  it  rises  above  the  swamps  like  a  railroad  grading. 
The  matter  here  is  coarser,  and  many  cobbles  and  large  pebbles  appear,  all 
well  rounded.     A  short  distance  west  of  where  Musquash  Stream  empties 


TOPSFIELD-OLD  STEEAM  SYSTEM.  91 

into  Big  Lake,  there  is  a  tliiii  sheet  of  gravel  on  a  gentle  slope  rising  but  a 
few  feet  above  the  lake.  This  gravel  lies  a  full  half  mile  south  of  the 
osar.  The  stones  are  distinctly  water-polished,  though  differing  little  from 
tillstones  in  shape.     This  deposit  is  an  old  beach,  either  marine  or  lacustral. 

The  osar  leaves  the  Musquash  Valley  about  a  mile  north  of  Big  Lake 
and  takes  a  nearly  straight  course  southwestward.  It  is  easily  traceable  for 
several  miles  along  the  northwestern  shore  of  Big  Lake,  often  forming  the 
beach.  The  gravel  reappears  on  the  southwestern  shore  of  the  lake, 
between  Little  Eiver  and  Little  Musquash  Stream,  and  continues  its  south- 
westward  course  for  several  miles  along  the  valley  of  Little  River.  It  then 
crosses  a  low  divide  and  extends  for  many  miles  southward  along  Old 
Stream,  expanding  into  extensive  plains  of  reticulated  ridges  near  the  Old 
Stream  Lakes.  The  sand  and  gravel  plains  extend  to  the  junction  of  this 
stream  with  the  Machias  River,  and  toward  the  south  are  quite  level  on  the 
top  and  present  the  appearance  of  a  marine  delta-plain. 

A  series  of  discontinuous  and  rather  flat-topped  plains  or  broad  ridges 
extends  from  near  Masons  Bay,  Jonesboro,  northward  into  Centerville. 
They  appear  to  be  marine  delta-plains,  deposited  not  in  the  open  sea  but 
in  bays  receding  backward  into  the  ice.  They  are  probably  a  continuation 
of  the  Topsfield-Old  Stream  system. 

The  extensive  marsh  regioa  penetrated  by  this  gravel  system  is  under- 
lain in  considerable  part  by  sedimentary  clay.  Big  Lake  is  189  feet  above 
high  tide.  Hence,  when  the  sea  stood  at  225  feet,  a  sheet  of  salt  water 
must  have  extended  up  the  valley  of  Schoodic  (also  called  Kennebasis) 
River  to  a  point  a  short  distance  west  of  Big  Lake,  and  at  an  elevation  of 
about  36  feet  above  the  present  level  of  the  lake.  The  region  around  the 
lake,  especially  toward  the  south  and  southwest,  is  so  low  that  a  body  of 
water  of  that  elevation  would  be  very  much  larger  than  the  present  lake. 
The  divide  between  Little  River  and  Old  Stream  is  low,  but  probably  not 
low  enough  for  an  arm  of  the  sea  to  have  extended  from  Big  Lake  down 
the  Old  Stream  and  Machias  valleys.  The  region  overgrown  with  pine 
near  Clifford  Lake,  which  I  formerly  supposed  was  covered  with  glacial 
gravel,  now  appears  to  owe  its  sand  and  gravel  to  the  action  of  the  waves ; 
they  are  probably  beaches  of  that  period.  There  is  an  enlargement  of  the 
osar  near  the  northwestern  angle  of  Big  Lake.  Part  of  this  appears  to  be 
a  small  delta.     If  so,  the  history  of  the  Topsfield-Old  Stream  glacial  river 


92  GLACIAL  GRAVELS  OF  MAINE. 

appears  to  be  as  follows :  First,  the  main  glacial  river  flowed  on  to  the  sea 
near  Jonesboro.  As  the  ice  retreated,  a  series  of  small  deltas  were  formed 
in  bays  or  lakes  within  the  ice.  The  great  delta-plain  in  T.  25  and  in 
Wesley  was  formed  when  the  ice  had  retreated  so  far  iip  the  Machias 
Valley  that  the  glacial  river  carried  its  sediments  beyond  the  ice  front  into 
the  open  sea.  Finallj',  Avhen  the  sea  stood  at  about  230  feet,  the  ice  had 
melted  so  far  to  the  northward  that  a  bay  of  salt  water  occupied  the  basin 
of  Big  Lake.  The  glacial  river,  now  greatly  reduced  in  size,  poured  into 
the  sea  near  the  northwestern  angle  of  Big  Lake,  and  perhaps  subsequently 
at  another  point  a  few  miles  northward  in  the  Musquash  Valley.  These 
apparent  deltas  near  Big  Lake  may  have  been  deposited  in  purely  glacial 
lakes,  3^et  they  bear  a  suggestive  relation  to  the  old  sea-level  in  the  basin 
of  the  lake. 

GRAND    LAKE    OSAE. 

At  the  foot  of  the  outlet  of  Grand  (Schoodic)  Lake  a  well-defined  osar 
extends  northward  into  the  lake  and  can  be  seen  for  some  distance  on  the 
floor  of  the  lake.  The  stones  are  so  well  rounded  that  it  seems  probable 
the  series  extends  north  or  northwest  of  this  point,  perhaps  to  Oxbrook 
Lake.  The  ridge  extends  southward  from  Grand  Lake  Stream  and  joins  the 
main  system  in  the  valley  of  Little  River.  Not  far  from  the  lake  the  ridge 
consists  of  very  coarse  matter.  The  large  size  of  the  bowlderets  and 
bowlders  makes  it  probable  that  the  ridge  was  deposited  by  a  subglacial 
stream.  The  upper  Schoodic  Lakes  lie  in  the  midst  of  a  granite  region 
which  has  contributed  a  great  number  of  stones  and  bowlders  to  the  drift. 
The  vast  quantities  of  granitic  drift  contained  in  the  g'reat  gravel  plains  of 
Hancock  and  AVashington  counties  came  chiefly  from  the  long  outcrop  of 
granite  which  extends  from  Orland  on  Penobscot  Bay  with  but  few  inter- 
ruptions through  New  Brunswick  to  Chaleur  Bay. 

FARM   COVE   GRAVELS. 

Farm  Cove  is  a  deeply  reentering  bay  on  the  south  shore  of  Grand 
Lake.  From  the  head  of  the  cove  a  low  pass  extends  southeastward, 
bordered  by  high  hills.  The  highest  point  of  the  pass  rises  but  a  few  feet 
above  Grand  Lake,  and  within  less  than  a  mile  from  the  lake  a  branch  of 
Little  River  takes  its  origin  and  flows  southeastward.  Water- washed  gravel 
is  reported  in  this  valle}".     The  present  outlet  of  Grand  Lake  is  cut  through 


BANCROFT-GEAND  LAKE  SYSTEM.  93 

a  mass  of  till,  and  it  is  possible  that  before  the  barrier  was  eroded  the  lake 
stood  at  a  high  enough  level  for  the  ivaters  to  discharge  from  Farm  Cove 
southeastward.  If  so,  these  gravels  are  partly,  perhaps  wholly,  valley 
di'ift.  I  have  not  personally  explored  this  series.  It  is  provisionally 
included  among  the  glacial  gravels. 

BANCROFT-GRAND    LAKE    SYSTEM. 

An  osar  crosses  the  Maine  Central  Railroad  about  a  mile  west  of 
Bancroft  station.  The  gravel  is  somewhat  rounded,  but  not  enough  to 
indicate  that  the  ridge  extends  very  far  to  the  north.  It  has  not  been 
explored  in  that  direction,  and  probably  extends  only  a  few  miles.  With 
numerous  gajDS  the  gravel  takes  a  southeast  course  across  the  valley  of 
the  Mattawamkeag  River,  thence  over  a  low  divide  and  obliquely  across 
the  valley  of  Hawkins  Brook,  then  over  another  low  pass  into  the  valley 
of  Hot  Brook.  It  then  turns  more  nearly  southward,  and  near  the  Hot 
Brook  Lakes  it  expands  into  a  plain  about  one-third  of  a  mile  wide.  Part 
of  this  plain  has  the  extei-nal  appearance  of  a  delta,  and  was  probably 
deposited  in  a  small  glacial  lake,  such  as  would  naturally  form  on  a  north 
slope.  Thence  the  gravel  system  goes  south  along  the  valley  of  the  east- 
ern branch  of  Hot  Brook.  At  the  road  from  Danforth  to  Prentiss  the 
gravel  takes  the  form  of  a  low  osar-plain  in  the  bottom  of  the  valley. 
This  has  been  eroded  by  the  stream  into  terraces,  so  as  to  appear  like 
valley  drift,  but  the  stones  are  much  more  rounded  than  the  till  gravel 
which  appears  in  the  beds  of  small  brooks  in  that  part  of  the  State.  Cross- 
ing a  divide  said  to  be  much  less  than  200  feet  above  the  Hot  Brook  Lakes, 
the  gravels  turn  southeastward  over  a  rolling  region  to  near  the  northwest- 
ern angle  of  Baskahegan  Lake.  In  this  part  of  its  course  the  gravel  is 
somewhat  interrupted.  It  next  tuiTis  southwestward  through  Kossuth  to 
Pleasant  Lake,  crossing  the  valleys  of  several  streams  and  as  many  low 
divides.  In  this  section  it  is  a  two-sided  ridge,  and  is  not  quite  continuous. 
It  would  be  contrary  to  general  analogy  for  this  long  osar  stream  to  have 
ended  so  far  from  the  sea  as  Junior  Lake.  Rounded  gravel,  in  the  form  of 
ridges  and  terraces,  is  repoi'ted  along  Junior  and  Scraggly  lakes,  which  I 
infer  are  part  of  this  system.  They  appear  only  at  intervals,  and  probably 
a  large  part  of  the  gravel  is  beneath  the  water.  The  gravels  are  well 
developed   along   the  western    shore    of   Grand    Lake,    and   thence    thev 


94  GLACIAL  GRAVELS  OP  MAINE. 

continue  southwai'd  along  Pocumpus  and  Wabos  (or  Wabosses)  lakes,  to 
near  tlie  sotitli  end  of  ]\Iachias  Third  Lake.  The  accounts  as  to  its  course 
from  this  point  south  are  conflicting.  According  to  some  accounts  the 
gravel  continues  southeastward  and  imites  Avith  the  Topsfield  system  near 
the  head  of  Old  Stream;  according  to  others  the  gravel  is  nearly  contin- 
uous down  the  Machias  Valley,  part  of  the  way  keeping  back  from  the 
river.  On  general  grounds  the  latter  appears  to  be  the  more  probable 
course  of  this  large  glacial  river,  since  the  great  "Mont  Eagle  plains"  and 
the  "Raceground"  demand  a  large  and  long  river  as  their  origin.  But 
whatever  doubts  attach  to  the  course  of  this  system  in  the  vicinity  of 
Machias  Second  Lake,  there  is  no  doubt  that  a  system  of  gravels  extends 
from  Machias  First  Lake  southward  along  the  west  side  of  the  Machias 
River,  expanding  into  a  broad  series  of  plains  in  T.  30,  known  to  the  deer 
hunters  as  the  "  Racegroxmd."  The  part  of  these  plains  near  the  Air  Line 
road  (Calais  to  Bangor)  is  very  level  and  is  a  delta-plaiu.  Sedimentary 
clays  cover  the  valley  of  the  Machias  River  all  the  way  from  this  point  to 
tlie  sea,  which  makes  it  probable  that  the  southern  portion  of  the  Race- 
ground  is  a  marine  delta.  The  glacial  gravels  continue  southward  over  a 
gently  rolling  plain  and  cross  the  Mopang  River,  where  they  expand  into 
an  extensive  series  of  sand  and  gi-avel  plains,  known  as  the  "Mont  Eagle 
plains."  These  plains  are  reported  to  contain  in  places  kettleholes  and 
ridges,  while  in  general  they  are  quite  level  on  the  top.  This  indicates 
that  in  part  at  least  the  Mont  Eagle  plains  are  a  marine  delta.  In  regard 
to  the  section  extending  from  this  point  to  the  road  from  Columbia  Falls  to 
Jonesboro  my  information  is  quite  conflicting.  The  map  shows  the  system 
as  extending-  past  Libby  Lake  and  becoming  discontinuous  toward  the 
south,  endmg  near  Masons  Bay,  Jonesboro.  The  plains  in  Columbia  Falls 
and  Jonesboro  are  in  general  quite  flat  on  the  top,  and  show  much  coarser 
matter  on  the  north  and  west  than  farther  south  and  east.  This  indicates 
that  in  part,  if  not  wholly,  they  are  delta-plains,  deposited  in  reentering 
bays  in  the  ice  or  in  glacial  lakes. 

Length  from  Bancroft  to  Masons  Bay  about  85  miles. 

SISLADOBSIS-PLEASANT    RIVER    SYSTEM. 

All  my  informants  are  agreed  that  a  ridge  or  horseback  of  gravel 
extends  from  Sand  Cove  at  the  south  end  of  Sisladobsis  Lake  nearly  south 


SEBOOIS-KINGMAN-OOLUMBIA  SYSTEM.  95 

to  Machias  Fourtli  Lake.  From  tliis  point  southward  I  have  followed  in 
great  part  the  information  given  hj  H.  R.  Taylor,  C.  E.,  of  Machias,  and 
the  late  Hon.  S.  F.  Perley,  of  Naples.  As  mapjDed,  the  system  runs  near 
the  town  lines  east  of  Sabao  Lake  and  the  large  Moj^ang  Lake,  and 
appears  to  end  near  Pleasant  River  Lake.  I  crossed  this  system  on  the 
Air  Line  road  in  1878,  but  could  not  at  that  time  distinguish  the  plains  as 
a  delta.  My  information  concerning  the  Pleasant  River  Valley  south  of 
the  lake  of  that  name  is  meager  and  conflicting.  As  seen  from  Columbia, 
the  valley  appears  to  have  a  gentle  slope  and  to  be  covered  with  marine 
clay  for  a  long  distance  northward.  It  seems  probable,  therefore,  that  the 
plains  near  Pleasant  River  Lake  end  at  the  south  in  a  marine  delta — 
at  least  that  would  account  for  the  system's  ending  so  far  from  the  sea. 

As  to  the  region  between  Sisladobsis  and  Nickatous  lakes,  I  have 
received  much  information  from  Messrs.  James  Belmore  and  S.  W.  Hay- 
cock, of  Calais;  also  from  D.  F.  Maxwell,  C.  E.,  of  St.  Stephen,  New 
Brunswick;  A.  J.  Darling,  of  Enfield;  John  Gardner,  of  Robbinston,  and 
many  others.  All  agree  that  in  that  region  there  are  large  tracts  of  sand 
and  gravel  overgrown  with  "Norway  jsine."  These  are  probably  glacial 
gravels,  but  my  informants  locate  them  with  reference  to  streams  and  lakes 
not  on  the  existing'  maps,  and  therefore  it  is  impossible  for  me  to  map  them 
even  approximately. 

Within  30  miles  from  Machias  are  perhaps  the  most  noted  grounds  for 
the  hunting  of  deer  to  be  found  in  the  older  portion  of  the  United  States. 
The  "Raceground"  is  so  called  because  favorable  to  the  chase.  These 
great  plains  are  due  to  the  large  glacial  rivers  which  poured  into  the  sea,  at 
a  time  when  the  Machias  Valley  as  far  north  as  the  Air  Line  road  was 
covered  by  a  broad  sheet  of  salt  water. 

SEBOOIS-KINGMAN-COLUMBIA    SYSTEM. 

A  short  ridge  of  glacial  gravel  is  foimd  in  Oxbow  Township,  Aroos- 
took County,  and  several  similar  ridges  are  reported  along  the  upper 
Seboois  Lakes.  It  is  as  yet  uncertain  whether  they  have  any  connection 
with  the  remarkable  system  now  to  be  described.  An  osar  of  unknown 
length  comes  southward  out  of  the  woods  to  the  north  shore  of  Seboois 
Second  Lake  in  T.  7,  R.  7,  Penobscot  County.  It  enters  the  water  on 
the  north  side  of  the  lake  and  reappears  on  the  south  shore,  and  thence 


96  GLACIAL  GEAVELS  OF  MAINE. 

extends  south  for  several  miles  along  the  west  side  of  the  Seboois  River 
to  the  road  leading  from  Patten  northwestward  to  Seboois  farm  and  Cham- 
berlin  Lake.  It  is  here  in  a  valley  of  natm-al  drainage  continuous  (by  the 
Seboois  and  Penobscot  rivers)  all  the  way  to  the  sea.  But  the  osar  leaves 
this  open  valley  and  turns  abruptly  eastward.  The  road  just  mentioned  is 
made  on  top  of  the  osar  for  a  half  mile  or  more,  when  the  road  turns 
southward  while  the  ridge  keeps  on  eastward,  up  the  valley  of  Hot  Brook, 
then  over  a  low  divide,  and  down  the  valley  of  Hay  Brook,  to  Upper  Shin 
Pond.  Here  it  rejected  another  slope  of  natural  drainage,  crossed  the 
pond,  and  then  went  over  a  low  divide  into  the  valley  of  Peasley  Brook. 
It  then  turns  soiith  and  follows  the  valley  of  this  brook  to  its  junction  with 
Fish  Stream,  about  1  mile  west  of  Patten.  In  this  valley  the  gravel  takes 
the  form  of  an  osar-plain,  extending  across  the  valley  or  forming  a  flattish- 
topped  terrace  on  one  side.  From  near  the  junction  of  Peasley  Brook  and 
Fish  Stream  a  low  valley  extends  for  several  miles  southward,  cut  off  on 
the  south  by  hills  about  200  feet  high.  Rejecting  this  valley,  the  osar 
river  turned  nearly  a  right  angle  eastward,  and  for  several  miles  follows 
the  valley  of  Fish  Stream.  Its  course  lay  through  Patten  Village,  but 
there  is  a  short  gap  in  the  gravel  deposits  at  that  place,  so  that  a  traveler 
on  the  north-and-south  road,  sees  no  signs  of  the  system.  About  4 
miles  east  of  Patten,  in  Crystal,  the  gravel  (here  in  the  form  of  a  two-sided 
ridge)  turns  another  right  angle  cpiite  abruptly  and  goes  south  and  south- 
west across  the  1,000-acre  bog.  This  bog  lies  near  the  top  of  the  low  and 
level  divide  between  the  waters  of  Fish  Stream,  flowing  north  and  east 
into  the  west  branch  of  the  Mattawamkeag  at  Island  Falls,  and  those  of 
the  Molunkus  River,  flowing  south.  Here  the  gravel  takes  the  form  of  low 
bars  and  narrow  osar-plains,  flanked  and  often  nearly  covered  by  peat  and 
water.  The  drift  of  the  upper  Molunkus  Valley  merits  study.  No  two- 
sided  ridges  appeared  at  the  places  examined  by  me,  but  the  river  is 
bordered  by  low  terraces  which  have  the  form  of  erosion  terraces  of 
ordinary  valley  di-ift.  An  inspection  shows  that  the  stones  of  this  gravel 
are  all  well  rounded,  much  more  so  than  the  ordinary  stream  gravel  in 
that  part  of  the  State.  We  know,  too,  that  a  large  glacial  river  flowed 
into  the  upper  end  of  this  valley,  and  it  is  also  certain  that  such  a  river 
flowed  in  the  southern  part  of  the  valley.  The  river  therefore  must  have 
flowed  the  whole  length  of  the  valley.     But  the  only  water-washed  gravel 


SEBOOIS-KINGMAN-OOLUMBIA  SYSTEM.  97 

found  in  the  upper  part  of  the  valley  is  that  plain  near  the  stream  having 
the  form  of  a  sheet  of  valley  drift  extending  across  the  whole  of  the  valley. 
From  these  considerations  and  the  very  round  shape  of  the  stones  it  appears 
that  the  gravel  along  the  Molunkus  for  several  miles  south  of  Sherman  is 
an  osar-plain  and  not  ordinary  valley  drift.  The  gravel  follows  the 
Molunkus  through  Sherman,  Benedicta,  and  Golden  Ridge.  Approaching 
Macwahoc,  it  takes  the  form  of  two-sided  reticulated  ridges  inclosing 
^several  kettleholes.  The  ridges  here  are  higher  and  steeper  than  they  are 
farther  north,  and  are  composed  largely  of  pebbles,  cobbles,  and  bowlder- 
ets.  The  Molunkus  Stream  empties  into  the  Mattawamkeag  River  a  short 
-distance  west  of  King-man.  For  12  miles  north  of  its  mouth  the  Molunkus 
flows  with  a  very  sluggish  current,  and  in  time  of  flood  overflows  its  broad 
-alluvial  plain  of  silty  sand  and  clay.  The  reticulated  ridges  at  Macwahoc 
were  deposited  at  the  foot  of  the  steeper  slope  of  the  valley.  From  near 
the  north  line  of  Macwahoc  to  Kingman  the  gravel  is  found  on  the  east 
side  of  the  Molunkus  and  at  a  distance  of  from  one-eighth  to  near  one-half 
.a  mile  from  it.  The  lateral  slopes  of  the  valley  are  gentlj'  inclined  toward 
the  west,  and  the  gravel  is  seldom  found  more  than  30  feet  above  the 
river.  In  respect  to  its  material  and  stratification,  this  plain,  situated  on 
the  side  of  the  hills  above  the  river,  is  exactly  like  the  low  plain  of  gravel 
which  fills  the  bottom  of  the  valley  farther  to  the  north  and  which  has  the 
external  form  of  a  plain  of  valley  drift.  But  the  plain  or  terrace  on  the 
side  of  the  hill  above  the  river  is  plainly  of  glacial  origin,  and  this  shows 
the  origin  of  the  plain  in  the  bottom  of  the  valley  farther  north.  They 
difl"er  in  no  respect  except  situation  with  respect  to  the  river. 

South  of  Macwahoc  the  gravel  becomes  finer,  and  then  comes  an  inter- 
esting study.  For  2  miles  north  of  Kingman  we  find  a  uorth-aud-south 
line  of  ridges  of  fine  sand.  The  large  alluvial  plain  of  the  Molunkus  lying 
to  the  west  could  have  furnished  sand  which  the  west  winds  might  drift  up 
the  hill.  The  question  arises.  Are  these  ridges  and  terraces  of  sand  really 
the  osar  or  are  they  blown  sand  ?  I  have  seen  great  numbers  of  sand  dunes 
in  various  parts  of  the  State,  but  never  any  north-and-south  ridges  showing 
such  steep  lateral  slopes  as  these  or  forming  a  naiTOw  and  neai'ly  continuous 
ridge  for  2  or  more  miles.  I  therefore  conclude  that  this  sand  is  the  osar. 
The  ridge  is  well  developed  at  the  cemetery'  in  the  northwestern  part  of 
Kingman  Village,  where  the  railroad  has  cut  tlu-ough  it  to  a  depth  of  about 
MON  xxxiv 7 


98  GLACIAL  GRAVELS  OF  MAINE. 

15  feet.  South  of  this  pomt  the  glacial  river  crossed  the  valley  of  the  Mat- 
tawamkeag  River.  No  sand  or  gravel  is  visible  in  the  valley  for  half  a 
mile  or  more;  such  deposits  may  perhaps  have  been  laid  down  and  have 
been  washed  away  by  the  river  or  covered  out  of  sight  by  its  alluvium. 

At  Kingman  there  is  an  excellent  opportunity  to  compare  the  shapes  of 
the  stones  of  the  glacial  gravels  with  those  of  ordinary  stream  gravels.  The 
Mattawamkeag  River  at  this  place  has  cut  down  through  a  broad  ridge  or 
sheet  of  till  to  a  depth  of  30  or  40  feet,  and  has  deposited  the  stones  of  the 
eroded  till  as  a  narrow  plain  of  valle}'  drift  extending  down  the  valley  for 
about  one-fourth  of  a  mile.  A  series  of  rapids  existed  at  this  point  before 
the  building  of  the  dam;  and  directly  after  the  melting  of  the  ice-sheet, 
when  the  fall  must  have  been  30  or  more  feet  higher  than  at  present,  the 
rapids  and  waterfalls  must  have  formed  quite  a  cataract.  While  the  deep 
cut  was  being  eroded  the  stones  of  the  till  must  have  been  subjected  to 
much  more  abrasion  than  is  common  except  in  case  of  the  steeper  mountain 
valleys,  yet  they  preserve  their  till  shapes  ver}^  well.  Their  surfaces  are 
polished,  and  the  apices  of  the  angles  are  more  rounded  than  those  found 
in  the  beds  of  the  rivers  and  streams  of  Maine,  except  near  the  White  Moun- 
tains and  in  the  valleys  followed  by  the  glacial  rivers.  Their  shapes  are 
far  nearer  the  angular  and  subangular  shapes  of  the  tillstones  than  those 
of  the  glacial  gravel.  As  one  sees  how  much  more  rounded  the  stones  of 
the  osai-s  are  than  this  stream  gravel  at  a  place  favorable  to  attrition,  he  can 
not  fail  to  be  impressed  with  the  great  amount  of  attrition  and  frequent 
changes  of  position  to  which  the  stones  of  the  osars  owe  theii-  shapes.  The 
alluvium  of  the  Mattawamkeag  River  consists  of  fine  sand  and  clay,  except 
for  short  distances  near  the  rapids  and  waterfalls. 

The  dam  at  Kingman  originally  extended  from  a  bank  of  solid  till  on 
the  north  to  the  terrace  of  rolled  gravel,  cobbles,  bowlderets,  and  bowlders 
before  described.  Twice  in  time  of  high  water  this  loose  gravel  on  the 
south  side  of  the  river  has  been  undermined  and  eroded  by  the  water  fall- 
ing over  the  dam  until  the  water  escaped  around  the  south  end  of  the  dam. 
It  thus  happens  that  the  dam  is  now  twice  as  long  as  it  was  originally  and 
the  channel  is  miich  broader  at  the  dam  than  it  is  a  short  distance  below. 
At  the  time  of  my  visit  the  water  was  flowing  through  three  chutes  near  the 
bottom  of  the  dam,  situated  at  intervals  of  about  12  feet.  Between  these 
swift  streams  two  ridges  of  coarse  gravel  had  collected  beneath  the  water. 


SEBOOIS-KINGMAN-GOLUMBIA  SYSTEM.  99 

The  ridges  were  thus  flanked  on  each  side  by  a  stream.  About  30  feet 
below  the  dam  these  two  ridges  were  connected  by  a  transverse  ridge,  thus 
inclosing  a  kettlehole  about  ]0  feet  deep.  Here  is  well  illustrated  one  of 
the  ways  in  which  reticulated  kame  ridges  inclosing  basins  and  depressions 
are  deposited  by  glacial  streams  as  they  shoot  swiftly  out  of  their  narrow 
channels  or  tunnels  into  a  broader  channel  or  into  a  lake  or  the  sea. 

Not  far  south  of  the  Mattawamkeag  the  osar  begins  again  and  con- 
tinues somewhat  interruptedly  through  Webster  to  the  Mattagordus  Stream, 
in  Prentiss.  It  then  follows  the  valley  of  this  stream  for  several  miles  south- 
ward, expanding  into  a  sei'ies  of  reticulated  ridges  inclosing  kettleholes 
The  gravel  here  is  very  coarse,  and  cobbles,  bowlderets,  and  bowlders 
abound.  Near  the  northwest  corner  of  Springfield  the  system  turns  south- 
west. It  crosses  the  road  from  Springfield  to  Lee  about  midway  between 
those  villages,  consisting  at  that  point  of  a  low  plain  of  well-rounded  gravel 
which  incloses  a  small  lake,  the  source  of  one  branch  of  Mattakeunk  Stream. 
Just  north  of  the  road  is  a  broad  dome  or  hummock  of  morainal  aspect, 
since  it  is  strewn  with  many  bowlders  2  to  4  feet  in  diameter.  Examina- 
tion of  these  bowlders  on  faces  not  weathered  shows  that  they  have  been 
polished  by  water.  These  bowlders  are  granitic,  like  the  far-traveled 
bowlders  of  the  surrounding  district,  while  the  osar-plain  near  it  is  com- 
posed largely  of  slate  and  schists,  like  the  local  rock.  The  lower  parts  of 
the  till  of  that  region  are  mostly  derived  from  local  schists  and  calcareous 
and  argillaceous  slates.  In  the  region  east  and  northeast  of  Mount  Chase 
and  Patten  numerous  granite  outcrops  have  contributed  a  great  number  of 
granite  bowlders,  and  they  are  found  covering  the  slaty  till  for  many  miles 
to  the  south.  The  granite  bowlders  in  Springfield  and  Lee  are  unusually 
numerous,  and  there  may  possibly  be  an  outcrop  of  granite  somewhere  to 
the  south  of  the  Mattawamkeag,  but  careful  inquiry  has  failed  to  find  it. 

The  situation  may  be  summed  up  as  follows:  The  osar-plain  at  this 
point  is  composed  chiefly  of  the  same  material  as  the  lower  part  of  the  till, 
while  the  outlying  hummock  resembles  in  composition  the  upper  till.  The 
osar-plain  shows  few  or  no  bowlders,  while  the  hummock  is  largely  com- 
posed of  them.  The  base  of  the  outlying  ridge  is  but  little  higher  than 
the  osar-plain.  Evidently  the  conditions  under  which  these  deposits  were 
formed  were  diff'erent  in  the  two  cases.  There  are  numerous  swells  and 
ridges  of  till  near  this  place.     During  the  final  melting  of  the  glacier  the 


TOO  GLACIAL  GRAVELS  OF  MAINE. 

ice  might  for  a  time  continue  to  flow  across  the  valle}^  until  checked  by  the 
hills  of  Springfield  and  Lee,  and  the  remarkable  mounds  of  till  may  par- 
take of  the  nature  of  a  terminal  moraine.  The  mound  of  glacial  gravel 
lying  near  the  osar-plain  may  date  from  this  period.  I  could  find  no 
signs  of  a  glacial  stream,  a  lateral  tributary  of  the  main  river,  reaching 
farther  north  than  this  mound.  The  very  large  size  of  the  bowlders  of  the 
mound  indicates  that  it  was  formed  subglacially  and  makes  it  probable  that 
the  deposit  is  partly  or  Avholly  a  water-washed  terminal  moraine.  The 
region  deserves  more  careful  study  than  I  have  been  able  to  give  it. 
Apparently  the  upper  ice-bearing  granite  bowlders  from  the  north  contin- 
ued to  flow  over  the  lower  ice  after  the  latter  was  partially  embayed.  The 
osar-plain  soon  crosses  a  low  divide  at  an  elevation  near  200  feet  above 
Kingman,  and  then  follows  the  valley  of  the  Passadumkeag  River  to  Nick- 
atous  Stream,  where  it  turns  from  its  southwestward  course  to  south.  It 
here  takes  the  form  of  a  two-sided  ridge  80  feet  high  (at  an  elevation  above 
the  sea  of  380  feet,  as  determined  by  spirit  level  by  D.  F.  Maxwell,  C.  E.), 
and  continues  as  a  prominent  ridge  for  several  miles  southward.  It  then 
turns  more  nearly  southeastward  and  follows  the  Narraguagus  Valley  for 
many  miles,  most  of  the  way  lying  one-fom-th  of  a  mile  or  more  to  the 
west  of  the  river.  Part  of  the  way  it  takes  the  form  of  a  single  two-sided 
rido-e;  at  other  places  it  is  an  osar-plain  one-eighth  of  a  mile  or  more  in 
breadth,  and  occasionally  it  expands  into  narrow  plains  of  reticulated  ridges. 
North  of  Lead  Mountain,  in  Beddington,  an  osar-ridge  composed  almost 
wholly  of  bowlderets  and  bowlders  is  found  on  the  eastern  border  of  the 
o-ravel,  while  to  the  west  extends  a  plain  of  sand  and  gravel  1  to  3  miles 
wide.  The  western  portion  of  these  plains  shows  some  low  sand  dunes. 
But  for  the  wind,  the  plains  would  probably  now  be  quite  level  on  top.  The 
material  plainly  becomes  finer  as  we  go  westward.  The  plain  was  a  delta 
deposited  in  a  glacial  lake  or  in  the  sea.  Its  elevation,  by  aneroid,  is  more 
than  300  feet  above  sea  level. 

Just  south  of  Lead  Mountain  there  is  another  gravel  plain  of  rounded 
shape,  about  three-fourths  of  a  mile  in  diameter.  It  ends  in  a  steep  bank 
downward  both  on  the  west  and  south,  beyond  which  is  till,  not  a  plain  of 
clay.  It  is  gently  rolling  on  the  top,  yet  shows  finer  sediments  on  the  west 
and  south,  and  must  have  been  deposited  in  an  open  body  of  water.     The 


SEBOOIS-KINGMAiv"COLUMBIA  SYSTEM.  IQl 

following  considerations  make  it  probable  that  both  this  plain  and  the  one 
north  of  Lead  Mountain  were  deposited  in  glacial  lakes  rather  than  in  the 
sea :  First,  the  contour  of  240  feet  lies  several  miles  south  of  here,  not 
more  than  3  or  4  miles  north  of  Deblois  Village ;  second,  no  marine  sands 
or  clays  are  found  in  the  valley  of  the  Narraguagus  far  to  the  north  of 
Deblois,  whereas  the  basin  of  Beddington  Lake  ought  certainly  to  be  cov- 
ered with  marine  clay  if  the  sea  formerly  extended  north  of  Lead  Mountain; 
third,  the  fact  that  the  plain  south  of  Lead  Mountain  ends  in  a  rather  steep 
bank  on  the  west  and  south  is  most  easily  explained  on  the  hypothesis  that 
a  glacial  lake  was  there  bordered  by  walls  of  ice.  At  Upper  Beddington 
the  osar-plain  once  filled  the  whole  valley  of  the  Narraguagus  to  a  height 
of  50  feet  and  a  breadth  of  about  one-eighth  of  a  mile,  though  the  river  has 
now  deeply  eroded  the  gravel  along  the  axis  of  the  valley.  Going  north- 
ward a  short  distance,  we  find  the  glacial  gravel  leaving  the  valley  and 
keeping  off  to  the  west  on  ground  30  to  75  feet  above  the  river.  Above 
this  point  there  is  but  little  gravel  of  any  kind  in  the  bed  of  the  Narra- 
guagus. The  valley  drift  is  scanty,  and  the  stones  it  contains  are  plainly 
tillstones,  which  have  lost  but  little  of  their  till  shapes,  a  great  contrast  to 
the  very  round  stones  of  the  osar-plain  that  fills  the  valley  at  Upper  Bed- 
dington. Now,  if  at  the  time  the  delta-plain  north  of  Lead  Mountain  was 
being  deposited  the  sea  occupied  the  valley  of  the  Narraguagus  as  far  north 
as  that  place,  then  no  reason  can  be  given  why  the  glacial  gravel  should 
not  spread  across  the  open  valley  as  it  did  at  Upper  Beddington,  instead  of 
being  deposited  so  abundantly  to  the  west  of  the  river  and  on  land  consid- 
erably higher.  These  appearances  are  just  as  if,  during  the  final  melting 
of  the  ice,  a  tongue  of  ice  or  a  local  glacier  continued  to  flow  down  the 
unobstructed  north-and-south  valley  of  the  Narraguagus,  while  to  the  west, 
in  the  lee  of  hills  that  obstructed  the  ice  flow,  the  ice  had  already  melted,  not 
being  replenished  from  the  north,  hke  the  glacier  in  the  open  valley.  On 
this  theory  the  ridge  of  bowlderets  and  bowlders  lying  on  the  east  side  of 
the  plain  north  of  Lead  Mountain  may  in  part  be  a  water-washed  lateral 
moraine  of  the  hypothetical  valley  glacier. 

The  gravels  of  this  series  appear  on  the  shores  and  islands  of  Bedding- 
ton Lake  and  then  expand  into  broad,  rather  level-topped  plains  that  are 
continuous  with  the  great  Deblois-Columbia  plains,  which  will  be  described 


102  GLACIAL  GRAVELS  OF  MAINE. 

in  connection  with  the  Katahdin  system.  It  has  not  been  possible  thus  far 
to  distinguish  in  these  plains  the  gravels  brought  down  by  the  respective 
glacial  rivei's. 

The  amount  of  sediment  transported  by  this  long  osar  river  is  ver}^ 
great.  The  more  noticeable  features  of  this  gravel  system  are  the  fol- 
lowing: For  most  of  its  course  the  gravel  takes  the  form  of  a  two-sided 
ridge  (osar  proper)  with  arched  cross  section.  At  intervals  are  found 
several  reaches  of  a  low,  broad  ridge  or  plain,  rather  flat  on  top  in  cross 
section,  but  in  longitudinal  section,  both  up  and  down,  parallel  with  the 
surfaces  passed  over  by  the  system.  The  stratification  of  this  plain  is  rather 
horizontal  or  slightly  arched  in  cross  section.  To  this  plain-like  enlarge- 
ment of  the  osar  I  have  given  the  name  broad  osar,  or  osar-plain.  In 
places  this  plain  enters  a  valley,  and  it  then  for  some  miles  fills  the  bottom 
of  the  valley  from  side  to  side,  like  a  plain  of  valley  drift,  and  is  often 
eroded  into  terraces.  The  broad  osar  in  such  situations  is  readily  distin- 
guished from  valley  alluvium  by  the  more  rounded  shape  of  the  pebbles 
and  by  the  fact  that  the  jjlain  soon  leaves  the  valley  and  is  found  on  the 
hillsides  where  no  ordinary  stream  could  have  deposited  it,  the  pebbles  and 
all  other  features  exactly  resembling  that  portion  of  the  plain  found  in  the 
valley.  On  the  north  it  originates  about  700  feet  above  the  sea,  and  it  ends 
in  Columbia  but  a  few  feet  above  high  tide.  Five  times  it  leaves  large 
valleys  of  nat^^ral  drainage  and  crosses  hills  into  other  valleys,  besides 
crossing  many  minor  elevations.  Its  remarkable  meanderings  are  in  gen- 
eral determined  by  the  relief  forms  of  the  land,  since  it  does  not  cross  hills 
more  than  about  200  feet  liigh,  measui-ed  on  the  north,  but  it  does  not  always 
follow  the  lowest  passes.  Reaches  of  fine  matter  alternate  with  coarse, 
and  where  the  coarsest  matter  appears  the  system  generally  takes  the  form 
of  reticulated  ridges  inclosing  basins.  The  most  abundant  deposits  of 
large  stones  and  bowlders  are  in  the  granitic  region  of  the  lower  Narra- 
guagus  Valley.  North  of  Springfield  there  are  only  two  places  where  the 
stones  are  ver}-  large:  One  in  Prentiss,  at  the  middle  of  a  long  slope  of  15 
miles  northward,  and  one  at  Macwahoc,  near  the  middle  of  a  southward 
slope  of  more  than  20  miles.  Intermediate  between  these  two  points  (near 
Kingman,  at  the  bottom  of  the  deepest  valley  which  the  system  crosses) 
the  material  is  unusually  fine,  i.  e.,  fine  sand.  The  gaps  in  this  gravel  system 
are  less  numerous  and  shorter  than  in  sliix  other  of  the  lonff  systems. 


WINN-LEE  GRAVELS.  103 

"  Norway  pine "  plains. — In  westei'ii  MaiiiG  R  growtli  of  the  various  yellow 
pines  known  locally  as  "Norway  pine"  is  a  proof  of  the  presence  of 
reticulated  kame  ridges.  In  eastern  Maine  such  pines  are  often  found  on 
delta-plains  of  nearly  horizontally  stratified  sand  and  gravel,  some  of  which 
are  special  sediments  deposited  in  the  sea.  The  presence  of  a  yellow-pine 
growth  is  indicative  of  water-washed  matter,  and  that  is  about  all  that  I  am 
yet  able  to  affirm  of  eastern  Maine. 

Length  of  the  Seboois-Kingman-Columbia  system,  about  125  miles. 

WINN-LEE    GRAVELS. 

A  line  of  glacial  gravels  extends  nearly  north  and  south  along  the 
valley  of  the  west  branch  of  the  Mattakeunk  Stream.  It  passes  through 
ihe  eastern  part  of  Winn  into  Lee.  Most  of  the  way  these  gravels  take  the 
form  of  an  osar-plaiiL  At  Lee  Village  this  plain,  which  is  there  nearly 
one-fourth  of  a  mile  wide  and  rises  10  to  30  feet  above  the  surrounding 
till,  becomes  somewhat  reticulated  and  incloses  a  lakelet  and  trotting 
track.  Southeast  of  Lee  Village  the  gravels  become  somewhat  discontin- 
uous, yet  the  gravel  can  readily  be  traced  over  the  southwestern  spur  of  a 
high  hill  and  thence  more  nearly  east  along  a  low  valley  to  join  the  main 
system  not  far  from  the  Passadumkeag  River,  east  of  ISIo.  3  Pond.  It  is 
uncertain  whether  this  series  has  any  northern  connections.  A  well-defined 
•osar  extends  from  the  Penobscot  River  for  3  or  more  miles  northward  along 
-the  valley  of  the  Mattakeunk  Stream.  The  glacial  stream  which  deposited 
it  probably  flowed  farther  than  this  place.  Its  probable  course  was  from 
■  the  mouth  of  the  Mattakeunk  southeastward  along  the  Penobscot  Valley  to 
Mattawamkeag,  thence  up  the  valley  of  the  Mattawamkeag  River  to  the 
Mattakeunk  Stream,  and  thence  along  this  valley  to  Lee.  Yet  it  is  some- 
what difficult  to  make  out  the  connection  with  certainty.  Mattawamkeag 
Village  stands  upon  a  terrace  of  well-rounded  gravel  at  an  elevation  of 
.about  190  feet.  At  the  time  the  sea  stood  at  230  feet,  the  Penobscot  Bay 
of  that  time  would  extend  beyond  Mattawamkeag  up  both  the  Penobscot 
and  Mattawamkeag  valleys.  If  a  plain  of  glacial  gravel  were  deposited 
in  these  valleys,  the  tidal  cuiTents  would  subsequently  have  modified  and 
more  or  less  reclassified  the  surface  portion,  and  these  marine  sediments 
would  afterwards  have  been  more  or  less  acted  upon  by  the  rivers  after  the 
,sea  receded.     At  Mattawamkeag  we  have  to  distinguish  glacial,  marine. 


104  GLACIAL  GRAVELS  OP  MAINE. 

and  fluviatile  drift.  The  details  are  complex,  and  space  does  not  permit  a 
full  discussion  of  the  problem  The  most  probable  interpretation  of  the 
facts  is  that  we  have  all  three  forms  of  drift  represented  in  the  Mattawam- 
keag  terraces  and  that  the  glacial  river  followed  the  route  above  indicated. 

Length  from  Mattakeunk  to  No.  3  Pond,  about  15  miles. 

Several  narrow  terraces  of  water-washed  gravel  are  found  at  intervals 
in  the  valley  of  the  Penobscot  in  Winn  and  Lincoln.  They  are  found  at 
least  50  feet  above  the  Penobscot  River,  and  are  probably  sea  beaches. 

KATAHDIN   SYSTEM. 

This  is  an  extensive  osar  system,  deposited  by  a  very  large  glacial: 
river  which  drained  the  region  about  Mount  Katahdin  and  which  was- 
remarkable  for  the  number  of  its  tributary  branches.  It  is  uncertain  which, 
is  the  longest  tributary  of  this  i-ather  inaccessible  system. 

A  horseback,  or  two-sided  ridge,  passes  the  Seboois  farm,  near  the  west 
branch  of  the  Seboois  River  in  T.  6,  R.  7,  Penobscot  County.  It  is  known 
to  extend  3  miles  northward  into  the  forest.  It  passes  only  a  few  rods 
from  the  farmhouse  and  has  been  cut  through  at  this  point  by  a  road  to 
the  depth  of  12  feet.  The  stones  are  so  angular  that  at  first  sight  the  ridge 
appears  to  be  a  meandering  lateral  moraine.  A  more  careful  examination 
shows  that  the  finer  detritus  has  been  washed  out  of  the  mass  and  that  the 
stones  have  been  slightly  water  polished.  It  is  thus  proved  to  be  a  form  of 
glacial  gravel,  the  residue  left  after  the  till  had  been  washed  by  gentle  cur- 
rents. The  osar  can  be  traced  for  several  miles  southward  nearly  parallel 
with  the  west  branch  of  the  Seboois  River,  but  it  disappears  near  where 
this  stream  enters  the  remarkable  canyon  by  which  the  Seboois  penetrates 
the  Katahdin  highlands.  This  gorge  extends  from  near  the  junction  of  the 
two  branches  of  the  Seboois  River  almost  to  the  junction  of  this  river  with 
the  East  Branch  of  the  Penobscot.  For  several  miles  at  the  north  end  of 
this  wild  gorge  the  rocky  hills  slope  steeply  down  to  the  river,  and  there  is 
a  constant  succession  of  rapids;  naturally  there  is  but  little  water  drift  in 
this  part  of  the  valley.  Southward  the  valley  widens  here  and  there  and 
contains  a  plain  of  sand,  gravel,  cobbles,  and  bowlderets.  In  places  the  plain 
is  about  one- fourth  of  a  mile  wide  and  rides  30  or  40  feet  above  the  present 
bed  of  the  river.  From  one  to  three  terraces  of  erosion  border  the  river. 
The  stones  have  been  much  more  water  rounded  than  those  found  in  the- 


A.      LAKELET   SURROUNDED    BY   GLACIAL  GRAVEL;    LEE. 


B.      DOME  OF   COARSE  GRAVEL;  SPRINGFIELD. 


KATAHDIN  SYSTEM.  105- 

beds  of  the  present  streams  of  that  part  of  the  State,  and  are  more  rounded 
than  those  found  in  the  midst  of  the  rapids  of  this  stream  to  the  north  of 
the  plains  in  question.  The  valley  is  not  valley  drift,  but  is  an  osar-plain. 
The  hills  bordering  the  canyon  on  each  side  are  from  400  to  1,000  feet 
high.  It  is  certain  that  a  glacial  river  flowed  into  the  north  end  of  the 
gorge,  and  the  height  of  the  lateral  hills  is  such  that  it  could  not  escape 
except  along  the  valley.  The  Seboois  Valley  broadens  for  several  miles 
north  of  its  junction  with  the  East  Branch  of  the  Penobscot.  This  wide 
valley  is  bordered  by  plains  of  clay,  sand,  and  gravel,  and  so  also  is  the 
valley  of  the  East  Branch  of  the  Penobscot  from  this  point  to  Medway. 
Whether  any  part  of  this  is  an  osar-plain  I  can  not  now  be  certain.  At  the 
time  of  my  exploration  in  1879  I  had  not  diagnosed  the  level-topped 
osar-plains,  and  regarded  them  as  valley  drift.  The  sedimentary  plain  of 
these  valleys  is  from  near  half  a  mile  to  a  mile  or  more  in  breadth.  My 
notes  refer  to  certain  coarser  gravels  on  one  side  of  the  plain,  which  perhaps 
are  a  broad  osar.  A  well-defined  osar  begins  about  14  miles  north  of  Med- 
way and  extends  continuously  southward  to  that  place.  While  passing 
along  the  river  in  a  canoe  I  saw  no  osar  ridges  farther  north  from  Medway 
than  this.  This  ridge  is  bordered  on  the  east  by  the  river  and  then  by  a 
broad  sedimentary  plain  extending  for  many  miles  southward.  It  is  com- 
posed of  clay  overlain  by  sand  and  gravel,  all  very  nearly  horizontally 
stratified.  The  ridge  has  steep  lateral  slopes  on  both  east  and  west  sides. 
It  is  usually  densely  covered  by  vegetation  and  from  the  river  does  not 
appear  very  different  from  the  steep  bluff  of  erosion  in  the  alluvium  on  the 
east  bank  of  the  river.  None  of  the  geologists  who  passed  up  this  valley 
appear  to  have  noticed  the  ridge,  but  Thoreau  must  have  seen  it  and  recog- 
nized its  nature.  He  writes  (Maine  Woods,  p.  294):  "We  stopped  early 
and  dined  on  the  east  side  of  an  expansion  of  the  river  [East  Branch  of  the 
Penobscot]  just  above  what  are  probably  called  Whetstone  Falls,  about  a 
dozen  miles  below  Hunt's.  *  *  *  There  were  singular  long  ridges  here- 
abouts, called  horsebacks,  covered  with  ferns." 

In  a  few  places  the  osar  expands  into  oval  or  elongated  plains,  not  very 
broad,  but  rather  flat  on  top,  sometimes  inclosing  kettleholes. 

A  comparison  of  the  alluvial  drift  of  the  valleys  of  the  East  Branch  of 
the  Penobscot  and  Seboois  River  above  Medway  with  that  of  the  valleys  of 
Pleasant  River,  the  Piscataquis,  the  upper  Kennebec,  the  Carrabassett,  and 


106  GLACIAL  GRAVELS  OF  MAINE. 

the  Sandy,  shows  that  the  sedimentary  deposits  are  very  nearly  the  same 
in  all  of  them.  These  valleys  are  all  at  about  the  same  distance  from  the 
;sea  and  the  sediments  may  well  be  interpreted  by  comparison.  In  some 
of  these  valleys,  as  the  Pleasant  and  Carrabassett,  the  sediments  are  plainly 
overwash  or  frontal  plains,  composed  of  matter  that  was  brought  down  by 
glacial  streams  to  the  extremity  of  the  ice  and  then  spread  out  over  the 
bottoms  of  the  open  valleys.  They  mark  a  stage  in  the  retreat  of  the  ice 
when  it  still  lingered  in  the  upper  parts  of  these  valleys  and  practically 
formed  local  valley  glaciers.  Since  a  true  osar  river  flowed  from  the  north 
into  the  gorge  of  the  Seboois  River  and  also  in  the  lower  part  of  the  valley 
■of  the  East  Branch,  the  history  of  these  valleys  is  probably  this:  A  long 
•osar  river  at  one  time  flowed  throug'h  the  valleys.  Later  the  osar  expanded 
-to  an  osar-plain  in  the  gorge  of  the  Seboois  and  for  some  miles  down  the 
East  Branch.  Finally,  on  the  retreat  of  the  ice  the  lower  portion  of  these 
valleys  was  covered  by  a  frontal  plain  of  sediments  derived  from  the  glacial 
•streams  of  the  glacier  that  still  lingered  near  the  head  waters  of  the  Seboois 
Valley. 

At  Medway  this  osar  crosses  the  West  Branch  of  the  Penobscot,  and, 
■except  an  island  in  the  river,  has  been  washed  away  by  it.  The  osar  then 
follows  the  south  bank  of  the  river  for  about  3  miles,  being  washed  away  in 
;some  places.  Just  west  of  the  mouth  of  Pattagumpus  Stream  there  is,  on  the 
.south  side  of  the  river,  a  plain  of  high  reticulated  ridges,  forming  a  jumble  of 
hummocks  and  hollows.  The  gravel  here  is  coarser  than  the  average  of  tlie 
ridge.  The  osar  for  3  miles  has  been  taking  a  nearly  east  course,  and  directly 
before  it  \aj  the  broad  Penobscot  Valley.  The  osar  river,  lea^ang  this 
valley  of  natural  drainage,  turned  to  the  right  through  a  deflection  angle 
of  nearly  135°  and  took  a  southwest  course  up  the  Pattagumpus  Valley, 
then  over  a  low  divide  and  down  a  branch  of  Maddunkeuiak  Stream  into 
'Chester.  Near  the  Penobscot  River  it  turns  southwestward  and  follows  the 
west  side  of  that  river  for  several  miles,  and  then  at  the  north  end  of 
Hocamoc  Island  it  crosses  to  the  east  side  (PL  IV,  A).  The  north  end  of 
this  island  is  composed  in  part  of  the  osar  gravel.  South  of  this  point  the 
gravel  takes  the  form  of  a  series  of  massive  ridges  or  plains,  separated  by 
short  gaps.  These  ridges  are  20  to  50  feet  high,  and  are  rather  level  on  the 
•.top,  in  places  gently  rolling  and  containing  shallow  hollows.     The  system 


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^       OSAR   CROSSING    PENOBSCOT    RIVER,    HOCAMOC    ISLAND,    LINCOLN.      LOOKING    NORTH. 
The  bluff  aT  the  left  center  and  the  plain  at  the  right  are  composed  of  glacial  gravel.     The  osar  here  forms  a  broad  and  massive  tablt 


£.     OSAR    EXPANDED    TO   A    PLAIN;   SOUTH    LINCOLN.      LOOKING    NORTHWEST. 

The  hill  at  the  r'ght,  on  whicn  are  the  house  and  the  trees,  is  the  extension  of  the  level-topped  ridge  at  the  left.      The  gravel  mesa  here  shows  the 
steep  lateral  slopes  chaiacteristic  of  sediments  deposited  between  ice  walls. 


KATAHDIN  SYSTEM.  107 

passes  a  short  distance  east  of  South  Lmcohi,  and  soon  takes  the  form  of  a 
shigle  two-sided  ridge,  which  takes  a  southeastward  course  and  crosses  the 
Maine  Central  Railroad  a  short  distance  north  of  Enfield  station  (PL  V,  E). 
North  of  Lincoln  the  osar  is  chiefly  composed  of  small  fragments  of  slate, 
but  in  Enfield  it  passes  through  a  granitic  area  and  contains  many 
bowlderets  and  bowlders  of  granite,  up  to  2i  feet  in  diameter.  I  formerly 
regarded  the  numerous  bowlders  on  the  surface  as  having  been  dropped  by 
ice  floes.  The  proof  is  abundant  that  ice  floes  often  did  this,  but  recent 
excavations  in  the  osar  in  the  northern  part  of  Enfield  show  that  water- 
pohshed  bowlders  are  scattered  through  the  gravel  to  the  depth  of  at  least  8 
feet.  The  latter  are,  therefore,  a  true  part  of  the  osar,  though  there  are 
some  bowlders  on  the  surface  that  are  not  water-pohshed  on  what  seem  to 
be  unweathered  faces,  and  these  may  be  floe  bowlders.  The  ridge  here  is 
30  to  50  feet  high  and  of  arched  cross  section.  The  osar  passes  a  short 
distance  east  of  Enfield  station  and  then  traverses  a  great  clay-covered 
plaiia  in  the  towns  of  Passadumkeag,  Grreenbush,  and  Greenfield.  Much  of 
this  plain  is  as  level  as  the  prairies  of  the  West,  and  formed  part  of  the 
expanded  Penobscot  Bay.  The  flanks  of  the  osar  are  here  covered,  often 
deeply,  with  clays  containing  clams  and  other  marine  fossils.  Both  the 
clay  and  the  osar  are  sprinkled  with  occasional  bowlders  having  the  shapes 
of  till  bowlders.  There  is  nothing  like  a  sheet  of  till  overlying  the  clay, 
and  the  bowlders  indicate  the  work  of  ice  floes  rather  than  a  readvance  of 
the  glacier  after  the  deposition  of  the  clay.  It  is  noticeable  that  moi-e 
bowlders  were  stranded  on  the  hillsides  than  on  the  lowlands,  and  they  are 
most  numerous  on  the  north  sides  of  hills,  where  the  ice  floes  drifted  as  they 
made  their  way  down  the  bay.  The  Penobscot  Bay  at  the  time  the  sea 
stood  at  230  feet  was  15  or  more  miles  wide  from  east  to  west  at  this  point. 
In  one  place  near  the  north  line  of  Greenbush  so  many  bowlders  were  piled 
on  the  top  of  the  osar  that  no  attempt  has  been  made  to  plow  the  surface. 
A  road  is  made  on  the  top  of  the  osar  for  many  miles,  the  ridge  forming  a 
natural  roadway  through  the  level  and  sometimes  swampy  region.  The 
osar  here  seldom  rises  more  than  20  or  30  feet  above  the  plain  of  marine 
clay,  but  in  three  places  in  Greenbush  it  expands  into  a  series  of  broad  and 
plain-hke  ridges,  inclosing  some  kettleholes.  The  ridges  here  rise  above 
the  level  plain  to  a  height  of  100  feet.     Rising  so  abruptly  out  of  the  plain, 


108  GLACIAL  GKAVELS  OF  MAINE. 

they  are  very  prominent  landmarks  from  every  direction,  and  are  locally 
known  as  "  moinitains."  Their  material  is  rather  coarser  than  the  averaare 
of  the  osar,  and  shows  the  usual  sprinkling  of  stranded  bowlders. 

In  Greenfield  this  osar  unites  with  the  Howland  tributary.  Near  their 
junction  are  extensive  sand-and-gravel  plains  having  a  gently  rolling  surface. 
I  once  supposed  that  the  sea  had  washed  down  the  original  ridges  as  depos- 
ited by  glacial  streams  and  had  redeposited  them  with  a  nearly  horizontal 
stratification.  As  shown  elsewhere,  the  power  of  the  sea  to  erode  till  and 
glacial  gravel  was  very  limited  except  on-  the  most  exposed  coasts.  These 
plains  in  Greenfield  were  deltas  deposited  by  the  glacial  waters  near  where 
they  poured  into  the  sea,  or  possibly  into  a  large  glacial  lake. 

The  gravel  plain  continues  on  southward  along  a  branch  of  the  Sunk- 
haze  Stream.  Soon  the  plains  are  left  behind  and  we  find  an  osar  of  ordi- 
nary type,  often  of  very  large  size.  This  is  a  treacherous  wilderness,  and 
the  explorer  must  not  let  the  osar  get  out  of  his  sight  if  he  can  help  it. 
Just  as  he  approaches  the  head  of  the  Sunk-haze,  he  reaches  a  particularly 
aggravating  swamp.  With  many  misgivings,  he  concludes  to  trust  the  osar 
for  just  a  few  minutes  and  flank  the  swamp.  Arrived  at  the  other  side  of 
the  swamp,  it  is  just  as  he  had  a  right  to  expect.  The  osar  has  vanished. 
Before  him  is  the  top  of  the  divide,  dreary  with  bare  ledges  and  an  endless 
array  of  roches  moutonn^es  sprinkled  with  large  bowlders.  But  really  we 
are  dealing  with  rivers,  and  the  gravel  is  only  a  symbol.  A  mighty  osar 
river  certainly  came  from  the  north  to  this  place.  What  became  of  it?  It 
must  have  swept  over  that  divide  with  velocity  sufficient  to  enable  it  to  cany 
all  loose  matter  before  it  except  the  large  bowlders.  Still  we  must  seek 
field  evidence  that  it  passed  over  this  divide.  Going  east,  we  soon  descend 
to  the  Morrison  Pond,  a  long  narrow  body  of  water  situated  between  two 
high  granite  hills  which  slope  steeply  down  to  the  pond  fr'om  each  side. 
Within  a  half  mile  the  osar  reappears.  Round  cobbles  and  bowlderets 
soon  appear,  and  in  the  jaws  of  the  pass  take  the  form  of  a  large  windrow 
of  polished  bowlderets  and  bowlders  situated  on  the  south  side  of  the  pond. 
Then  for  a  mile  or  two  on  a  steep  down  slope  there  is  but  little  sediment  to 
represent  the  osar.  The  osar  river  crossed  the  west  branch  of  the  Union 
River,  and  immediately  we  find  a  broad  series  of  sand  and  gravel  plains 
in  Aurora  known  as  the  Silsby  Plains.  These  are  about  5  miles  long  and 
from  1  to  3  miles  wide.     Thev  extend  about  1  mile  north  of  the  outlet  of 


^^«5^,^  ^  -^^  ,    -I-    %  ^^^^ 


C^i; 


.1.     OSAR    FORKING    INTO   A    DOUBLE   RIDGE. 


KATAHDIN  SYSTEM.  109 

Morrison  Pond.  This  broad  plain  consists  of  nearly  horizontally  stratified 
sand  and  gravel,  the  material  becoming  finer  as  we  go  away  from  the  mouth 
of  the  outlet  of  Moi'rison  Pond.  This  proves  that  it  is  a  delta  deposited 
in  some  body  of  water.  These  plains  are  about  120  feet  above  the  sea,  and 
at  the  south  the  sand  passes  into  marine  clay,  which  covers  the  valley  of 
Union  River  from  this  point  all  the  way  to  the  coast.  It  is  therefore  evident' 
that  the  great  Katahdin  glacial  river  here  emptied  into  an  arm  of  the  sea 
which  extended  up  the  valley  of  Union  River  to  a  point  several  miles  above 
these  plains.  But  the  history  does  not  here  come  to  an  end.  From  near 
the  Morrison  Pond  outlet  a  ridge  or  series  of  ridges  of  coarse  gravel,  cob- 
bles, and  even  bowlderets,  extends  southeastward  across  the  Silsby  Plains. 
These  ridg-es  rise  above  the  surrounding  plain.  They  are  of  arched  cross 
section  and  are  clearly  of  different  origin  from  the  plain  of  nearly  horizon- 
tally stratified  gravel  and  sand  which  surrounds  them.  Near  the  Union 
River,  on  the  west  side  of  the  plain,  this  ridge  of  coarse  matter  is  inter- 
sected by  several  lower  transverse  ridges  which  are  parallel  with  the  trend 
of  the  valley,  and  it  is  also  deeply  cut  through  by  furrows  having  the  same 
direction.  Apparently  the  swift  tidal  cun-ents  as  they  swept  up  and  down 
the  valley  cut  furrows  through  the  ridge,  which  crossed  the  valley  obliquely, 
and  built  up  the  matter  as  transverse  ridges. 

The  facts,  so  far  as  known,  indicate  that  the  history  of  this  interesting 
localit)^  is  as  follows:  While  the  ice  was  still  deep,  the  glacial  river  flowed 
through  the  Morrison  Pond  Pass  and  so  on  obliquely  across  the  level  val- 
ley of  the  west  branch  of  Union  River,  where  the  Silsby  Plains  now  are, 
and  deposited  the  ridge  of  coarse  matter.  But  during  the  final  melting  of 
the  ice  the  sea  advanced,  and  finally  covered  all  the  valley  to  a  depth 
of  about  100  feet.  But  the  ice  to  the  north  in  the  Penobscot  Valley  was 
not  yet  melted,  and  the  glacial  river  continued  for  a  time  to  pour  its  freight 
of  sediment  into  the  bay,  and  the  tide  carried  the  finer  matter  far  and  near 
in  nearly  horizontal  stratification.  The  delta  thus  formed  extended  about  1 
mile  north  of  the  mouth  of  the  glacial  river  and  4  miles  south  and  south- 
east. While  this  was  going  on,  the  tides,  sweeping  up  and  down  the  val- 
ley, partially  washed  away  the  ridge  which  had  been  laid  down  before  the 
melting  of  the  ice,  cut  transverse  channels  through  it,  and  reclassified  the 
matter.  According  to  this  hypothesis,  the  Silsby  Plains  consist  of  an  older 
■osar  which  was  deposited  between  the  ice  walls  and  afterwards  bordered 


110  GLACIAL  GEAVELS  OF  MAINE. 

and  overlain  by  a  delta-plain  deposited  by  the  glacial  waters  in  an  open 
arm  of  the  sea. 

A  series  of  high  granite  hills  borders  the  valley  of  the  west  branch  of 
Union  River  on  the  east,  and  the  osar,  having  crossed  the  Silsby  Plains, 
ends  right  in  front  of  a  very  low  and  level  pass  between  two  of  the  hills. 
For  near  a  mile  in  this  pass  no  glacial  gravel  could  be  found,  but  at  the 
east  end  of  the  pass  the  gravel  begins  again  as  an  osar-plain  one-eighth  of 
a  mile  or  more  wide.  The  system  is  soon  cut  through  by  the  middle 
branch  of  Union  River  and  then  takes  the  osar  form  of  a  two-sided  ridge 
(PI.  V,  A).  This  ridge  rapidly  enlarges  toward  the  southeast  and  becomes 
known  as  the  Whalesback.  It  is  one  of  the  largest  I'idges  of  glacial  gravel 
in  Maine,  varying  in  height  from  50  to  100  feet  above  the  plain  of  marine 
clay  which  deeply  covers  its  base.  For  several  miles  a  parallel  smaller 
ridge  lies  a  short  distance  west  of  the  main  ridge,  and  the  two  are  con- 
nected by  numerous  cross  ridges.  Thus  are  inclosed  numerous  large  kettle- 
holes  and  swamps  containing  several  aci-es.  Among  the  local  legends,  I 
find  one  to  the  effect  that  Agassiz  was  greatly  interested  in  this  huge  ridge, 
speaking  of  it  to  my  informant  as  a  moraine.  The  Air  Line  road  from 
Calais  to  Bangor  is  made  on  the  top  of  this  ridge  for  about  3  miles.  The 
ridge  becomes  lower  toward  the  south,  and  the  Whalesback  is  considered 
to  end  at  this  low  place,  near  where  the  Air  Line  road  leaves  it  and  turns 
east.  The  gravel  does  not  end  here,  however,  but  continues  on  southeast- 
ward along  the  valley  of  Leighton  Brook,  a  tributary  of  the  middle  branch 
of  Union  River  flowing  northwest,  most  of  the  way  as  a  prominent 
two-sided  ridge.  Tn  the  eastern  part  of  T.  21  it  escapes  from  the  hilly 
country  into  the  great  plain  of  the  Narraguagus,  which  extends  for  many 
miles  to  the  sea.  It  at  once  expands  into  a  series  of  low  and  broad  reticu- 
lated ridges,  showing  a  gentle  rolling  and  hummocky  surface.  Soon  the 
o-ravels  become  more  level  and  horizontally  stratified.  They  extend  almost 
continuously  through  Ts.  22,  16,  and  Deblois,  into  Columbia.  Here  and 
there,  rising  above  the  horizontally  stratified  sediments,  are  ridges  of 
arched  cross  section  that  were  evidently  deposited  within  the  ice  walls. 
Most  of  these  plains  from  Rocky  Pond  and  southeastward  must  be  con- 
sidered as  a  marine  delta.  From  Columbia  to  Deblois,  and  perhaps  still 
farther  northwest,  the  southern  edge  of  the  gravel  plain  ends  in  a  steep 
bluflP  and  shows  so  many  cobbles  and  bowlderets  that  it  seems  quite  certain 


KATAHDIN  SYSTEM.  lH 

that  the  plains  were  bordered  by  ice  at  the  time  they  were  being  deposited. 
Not  far  west  of  Deblois  the  plain  ends  on  the  south  in  sand,  which  passes 
by  degrees  into  clay,  and  there  are  several  areas  of  sedimentary  clay  on 
the  north  side  of  the  sand  plain,  and  pai'tly  inclosed  by  it.  A  minute 
examination  may  show  that  some  of  them  were  laid  down  in  glacial  lakes. 
In  the  absence  of  direct  proof  to  the  contrary,  I  provisionally  assign  to  them 
all  marine  origin.  According  to  my  present  information,  the  most  prob- 
able interpretation  of  the  facts  is  this:  The  plains  southeast  of  Deblois 
were  deltas  deposited  Avithin  ice  walls,  i.  e.,  in  a  broad  channel  or  fiord 
inclosed  by  ice  at  the  sides,  but  open  to  the  ocean  in  front.  Subsequently, 
when  the  ice  had  all  melted  over  the  lower  part  of  the  Narraguagus  Valley,, 
the  Katahdin  glacial  river  flowed  into  the  open  sea  not  far  from  Rocky 
Pond  in  T,  22,  and  at  this  time  were  formed  the  large  delta-plains  situated 
west  and  northwest  of  Deblois.  The  situation  is  further  complicated  by  the 
fact  that  the  great  Seboois-Kingman  osar  river  was  at  the  same  time  form- 
ing a  marine  delta  in  the  Narraguagus  Valley  north  and  northeast  of  Deblois. 

The  eastern  end  of  the  United  States  Coast  Survey  base  line  is  situ- 
ated just  at  the  top  of  the  bluff  which  borders  the  Deblois-Columbia  Plains 
on  the  south.  Toward  the  east  the  plain  becomes  narrower  and  the  mate- 
rial coarser.  Near  Epping  Corner,  in  Columbia,  the  gravel  forms  a  plain 
near  one-half  mile  wide,  rising  from  40  to  more  than  100  feet  above  the 
marine  clays  which  border  it  on  the  north,  east,  and  south.  The  plains 
extending  from  here  northwestward  toward  Deblois  are  widely  known  in 
all  this  part  of  the  State  as  the  Epping  Plains.  Near  Epping  the  plain  is. 
rolling  and  ridged  on  the  top  and  contains  numbers  of  shallow  kettleholes. 
From  it  proceed  several  tongues.  On  the  north  three  of  these  tongues  pro- 
ject out  one-fourth  of  a  mile  or  more  toward  the  Pleasant  River.  The  val- 
ley of  this  river  is  here  a  broad  and  very  level  clay  plain,  and  the  ridges 
rising  steeply  100  feet  or  more  above  the  plain  form  a  very  prominent  line 
of  bluff's.  An  examination  of  the  map  shows  that  the  Seboois-Kingman 
and  the  Katahdin  osar  rivers  together  drained  near  one-fifth  of  the  southern 
slope  of  Maine,  and  that  all  this  vast  rush  of  glacial  waters  converged  at 
Epping — a  sufficient  cause  for  the  great  plains  of  Columbia,  Deblois,  and 
the  Narraguagus  Valley. 

A  tongue  of  glacial  gravel  extends  from  Epping  Church  southward  on 
the  road  to  Addison.     This  soon   becomes  discontinuous  and  the  gravel. 


112  GLACIAL  GEAVELS  OF  MAINE. 

hummocks  grow  smaller,  and  the  series  ends  within  about  2  miles.  To  the 
south  of  this  point  lies  a  low  clay  plain  all  the  way  to  the  sea  in  Addison. 
In  this  I  could  find  no  glacial  gravel  rising  above  the  clay.  The  only  east- 
Tvard  or  southward  connections  of  the  Epping  Plains  which  I  have  been 
able  to  find  are  certain  broad  plains  which  extend  through  Columbia  Falls 
eastward  toward  Masons  Bay,  Jonesboro.  In  the  midst  of  the  Deblois- 
Columbia  Plains  are  several  areas  of  till  rising  above  the  gravel  plains. 

Near  Epping  Church,  Columbia,  is  an  excavation  showing  an  interest- 
ing section.  On  the  top  is  a  thin  layer  of  well-rounded,  medium-sized 
gravel.  Beneath  this  is  a  stratum  2  to  4  feet  thick  containing  unpol- 
ished stones  and  bowlders  having  the  shapes  of  tillstones.  This  plain, 
being  below  the  contour  of  230  feet,  would  project  from  the  west  far  out 
into  the  expanded  bay  of  that  time  occupying  the  valley  of  Pleasant  River, 
and  would  be  much  exposed  to  stranding  ice  floes.  I  do  not  see  how  in 
general  the  scattered  and  isolated  bowlders  having  till  shapes  found  upon 
and  in  the  marine  clays  can  have  been  brought  to  their  present  positions 
except  by  ice  floes  or  small  bergs.  But  this  till-like  stratum  is  so  continuous 
that  I  see  no  objection,  so  far  as  the  mass  itself  is  concerned,  to  considering 
it  a  sheet  of  till.  The  till-like  mass  is  found  on  the  eastern  end  of  the 
high  plain,  and  does  not  extend  far  west  of  Epping  Corner.  This  is  where 
the  ice  floes  would  be  most  liable  to  run  aground,  and  it  is  a  point  in  favor 
of  the  ice-floe  theory.  I  saw  no  bowlders  distinctly  glaciated,  but  this  is 
not  fatal  to  the  theory  of  a  readvance  of  the  ice  after  the  deposition  of  the 
plain  of  g-ravel.  On  either  theory  the  surf  would  subsequently  beat  on  top 
of  the  plain  and  wash  down  some  of  the  highest  gravel  onto  the  adjacent 
till-like  mass,  though  in  man}^  places  there  is  no  overlying  beach  gravel. 
As  one  goes  over  much  of  the  plain  near  Epping  the  angular  or  unpolished 
bowlders  make  it  look  so  much  like  a  field  covered  by  ordinary  till  that  it 
needed  the  testimony  of  those  who  have  fruitlessly  dug  wells  to  a  great 
depth  to  convince  me  that  the  plain  is  underlain  by  100  feet  of  coarse 
glacial  gravel.  A  more  careful  exploration  of  the  whole  region  is  needed 
in  order  to  decide  the  question  of  the  origin  of  the  till-like  stratum.  At 
present  I  incline  to  favor  the  ice-floe  theory. 

Comparing  the  gravel  of  the  Katahdin  osar  with  the  till,  also  with  the 
country  rock  of  the  regions  through  which  it  passes,  we  find  that  both  the 
till  and  the  osar  are  made  up  chiefly  of  fragments  of  local  rocks  or  of  rocks 


A.      BROAD    PLAINS,    EXTENDING   FROM    COLUMBIA    FALLS   TO  JONESBORO.      LOOKING    EAST. 
The  hill  in  center  is  a  mesa  or  massive  plain  of  glacial  gravel  1  00  feet  high.     The  foreground  is  covered  with  marine  sediments. 


Ji      PLAIN    OF   GLACIAL   GRAVEL   CONTAINING   TILL-SHAPED    BOWLDERS;    NEAR    EPPING   CHURCH,    COLUMBIA 


KATAHDIN  SYSTEM.  113 

found  not  far  to  the  north.  Yet  there  has  plainly  been  a  transportation 
southward  along  the  line  of  the  osar  greater  than  the  distance  traveled  by 
the  till.  Thus,  north  of  Enfield  the  osar  consists  chiefly  of  slate.  It  there 
crosses  a  small  granite  area.  The  granite  immediately  appears  in  the  ridge, 
and  continues  to  be  largely  represented  in  it  for  10  or  15  miles  after  reenter- 
ing the  slate  region,  more  abundant  apparently  than  in  the  till  over  the 
slate  area.  Near  Morrison  Pond  the  osar  again  leaves  the  slate  area  and 
enters  the  g-reat  granite  area  extending  northeast  from  Orland  on  the 
Penobscot  Bay  nearly  all  the  way  to  Bay  Chaleur.  For  several  miles  after 
entering  the  granite  the  osar  contains  more  slate  than  the  till.  As  a  rough 
estimate,  I  compute  that  the  stones  of  the  osar  traveled  from  5  to  10  miles 
farther  than  those  of  the  till. 

For  most  of  its  coiirse  the  Katahdin  osar  is  closely  guarded  by  the 
wilderness.  Whoever  loves  the  large,  generous  works  of  nature,  unspoiled 
by  the  hand  of  man,  will  find  much  to  his  taste  in  following  this  osar.  A 
casual  crossing  of  the  system  is  insufficient  for  adequate  appreciation.  One 
needs  to  follow  it  for  100  miles  or  more  in  order  to  see  what  a  grand  geo- 
logical construction  it  is.  As  the  mighty  rampart  stretches  away  before 
him  day  after  day,  the  explorer  becomes  intensely  interested  in  watching 
its  varying  developments.  Railway  embankments  become  insignificant  in 
comparison  with  it.  It  is  perhaps  most  beautiful  in  the  midst  of  the  dark, 
silent  wilderness,  gray  with  lichens.  Its  vegetation  is  interesting  all  the 
way  from  Thoreau's  horseback,  covered  with  ferns;  past  days  and  days  of 
white  birch  and  poplar  growth;  past  the  hemlock  thickets  of  tlie  high  pin- 
nacles or  so-called  "mountains"  of  Greenbush,  where  Linnaea  and  Chiogenes 
vie  with  pipsissewa  and  Epigsea  in  decorating  the  huge  piles  of  gravel;  past 
the  checkerberry  plains  and  mosses  of  Greenfield  and  the  kame-inclosed 
sphagnous  swamps  of  the  Sunk-haze  wilderness,  lovely  with  calopogon, 
Pogonia,  and  Arethusa;  and  the  interest  keeps  up  even  to  the  great  blue- 
berry plains  of  Deblois  and  Columbia,  and  to  the  drosera-shining  spruce 
swamps  which  cover  the  unsightliness  of  the  cobbles,  bowlderets,  and 
rounded  bowlders  of  the  great  plains  near  Rocky  Pond. 

Not  less  interesting  are  its  topographical  relations.  By  the  time  one 
has  seen  the  osar  crossing  transversely  the  Penobscot  River  twice  and  the 
valleys  of  three  streams  to  their  source,  then  crossing  divides  and  descend- 
ing the  valleys  of  the   same  number  of  streams  flowing  in  the   opposite 

MON  XXXIV 8 


114  GLACIAL  GEAVELS  OF  MAINE. 

direction,  and  in  so  doing  taking  its  way  in  all  directions  from  southwest 
around  to  south,  southeast,  and  even  east,  by  this  time  one  will  see  how 
irresistible  is  the  proof  that  such  a  river  must  have  been  confined  between 
ice  walls  to  flow  so  independently  of  the  surface  forms  of  the  land.  Yet 
it  did  not  flow  wholly  independently  of  them.  It  nowhere  crosses  hills 
more  than  200  feet  laigher  than  the  ground  to  the  north  of  them,  and  thus 
it  penetrates  the  high  ranges  only  along  low  passes.  Traveling  southward, 
for  two  days  before  reaching  the  Morrison  Pond  Pass  I  had  observed  that 
remarkable  gap  through  them,  and  at  a  A'^enture  assigned  it  as  the  gateway 
of  the  osar  river.  For  a  day  and  a  half  after  the  idea  came  to  me  the  osar 
continued  a  nearly  south  course,  and  it  often  seemed  impossible  it  could 
go  so  far  to  the  east.  But  at  last  in  the  Sunk-haze  wilderness  it  described 
a  long  and  regular  curve  to  the  left  and  shot  straight  for  its  natural  outlet 
between  the  hills. 

This  osar  aifords  interesting  points  as  to  the  retreat  of  the  ice  north- 
ward before  the  advancing  sea.  To  say  nothing  of  the  delta-plains  depos- 
ited in  reentering  bays  or  broad  channels  within  the  ice  up  which  the  sea 
extended,  we  have  at  least  two  and  perhaps  three  series  of  delta-plains 
deposited  in  the  open  sea.  First,  the  ice  over  the  Narraguagus  Valle)^ 
melted,  so  that  the  delta-plains  west  and  northwest  of  Deblois  were  formed. 
Subsequently  the  ice  disappeared  over  the  valley  of  Union  River,  which 
then  became  covered  by  the  sea.  This  aiTested  the  further  flow  of  the 
glacial  river  southeastward.  For  a  time  it  continued  to  flow  into  the  bay 
of  the  Union  River  Valley,  and  the  Silsby  Plains  in  Aurora  were  thus 
deposited.  Still  later,  the  ice  receded  up  the  valley  of  the  Penobscot  until 
the  osar  river  probably  poured  into  the  broad  Penobscot  Bay  of  that  period 
in  Greenfield.  The  broad,  plain-like  ridges  near  the  Penobscot  River  at 
South  Lincoln,  though  deposited  between  ice  walls,  may  have  been  in  part 
due  to  the  checking  of  the  glacial  water  at  that  point  by  the  advance  of  the 
sea.  The  same  thing  may  have  happened  at  the  mouth  of  the  Pattagum- 
pus,  and  the  apparent  plains  of  valley  drift  near  the  junction  of  the  Seboois 
and  the  East  Branch  of  the  Penobscot  may  be  eitlier  flu^^aatile  or  estuarine 
drift,  brought  down  from  above  by  glacial  streams  while  the  country  to  the 
north  was  still  covered  by  ice.  The  pinnacles  of  Greenbush  and  several 
other  enlargements  of  the  gravel  deposits  were  probably  deposited  in  glacial 


KATAHDIN  SYSTEM.  115 

lakes  01'  in  a  plexus  of  sediment-clogg'ed  ice  channels  wliicli  were  practically 
equivalent. 

Length,  about  125  miles. 

STACEYVILLE-MEDWAY   BRANCH. 

A  nearly  continuous  ridge  begins  in  the  southern  part  of  Staceyville 
and  traverses  a  very  level  region  for  about  15  miles,  when  it  approaches 
the  Salmon  Stream.  Its  course  then  lies  along  the  west  side  of  that  stream 
for  several  miles,  and  not  far  north  of  the  Penobscot  River  it  expands  into 
plains  of  sand  and  gravel,  which  are  rather  level  on  the  top,  so  much  so  as 
to  make  it  probal^le  that  they  are  a  delta  deposit,  either  in  a  glacial  lake 
which  then  extended  across  the  Penobscot  Valley  and  for  a  short  distance 
up  the  valley  of  the  Pattagumpus  Stream,  in  an  estuary,  or  in  the  sea. 
The  sea  certainly  extended  for  several  miles  up  the  Penobscot  above  Mat- 
tawamkeag,  but  how  far  I  am  as  yet  unable  to  determine. 

Length,  about  20  miles.  Much  information  as  to  the  region  about 
Medway  has  been  received  from  Col.  J.  F.  Twitchell. 

SALMON  STREAM  BRANCH. 

This  has  been  traced  northward  along  the  valley  of  Salmon  Stream  to 
Salmon  Stream  Lake.  It  joins  the  Staceyville  branch  about  2  miles  north 
of  the  Penobscot  River. 

Length,  about  10  miles. 

SAM   AYERS   STREAM  BRANCH. 

This  osar  is  said  to  extend  as  a  two-sided  ridge  6  or  more  miles  along 
Sam  Ayei's  Stream,  above  its  junction  with  the  Mattamiscontis  Stream. 
The  connections  of  this  series  are  imcertain.  The  Champlain  sea  extended 
up  the  valley  of  the  Mattamiscontis  for  several  miles  above  South  Lincoln, 
and  if  this  short  glacial  stream  emptied  into  the  sea  at  some  place  in  that 
valley,  the  series  would  end  at  that  point  in  a  marine  delta.  If  so,  this  may 
be  an  independent  system.  But  I  found  several  domes  of  glacial  gravel  in 
that  valley  of  the  Mattamiscontis  nearly  opposite  South  Lincoln.  These 
may  be  either  an  extension  of  the  Sam  Ayers  Stream  series  or  simply  out- 
lying ridges  of  the  main  Katahdin  system,  which  lies  less  than  a  half  mile 
away  across  the  Penobscot.     My  own  exploration  did  not  extend  far  up 


116  GLACIAL  GRAVELS  OP  MAINE. 

the  Mattamiscontis  Valley.     I  provisionally  include  this  short  osar  among 
the  tributary  branches  of  the  Katahclin  system. 

MILINOKET    LAKEHOWLAND    BRANCH. 

This,  perhaps,  ought  to  be  considered  as  the  main  branch  of  the 
Katahdin  system. 

A  series  of  g-ravel  ridges  is  repoi'ted  by  J.  W.  Sewall,  C.  E.,  of  Old- 
town,  as  beginning  near  the  West  Branch  of  the  Penobscot  River  at  the 
mouth  of  Katahdin  Stream  and  extending  eastward  along-  the  valley  of 
Aybol  Stream  for  several  miles.  My  information  is  conflicting  and  rather 
indefinite  as  to  the  region  from  the  head  of  Aybol  Stream  eastward  to  Mili- 
noket  Lake.  On  a  down  slope  the  glacial  stream  must  have  continued  its 
flow  through  that  region,  but  if  it  left  any  gravels  in  its  channel  they  seem 
to  have  been  scanty  and  discontinuous,  just  as  happens  on  most  steep  down 
slopes  in  the  State,  and  not  to  have  attracted  the  attention  of  my  informants. 
South  of  Milinoket  Lake  a  nearly  continuous  osar  extends  along-  the  A^alley 
of  Milinoket  Stream  to  the  West  Branch  of  the  Penobscot  River,  at  the 
east  end  of  the  enlargement  of  the  river  known  as  Shad  Pond.  At  this 
point  the  ridge  contains  numerous  highly  rounded  pebbles  and  cobbles, 
showing  that  it  must  extend  for  a  long  distance  northward.  It  is  not  a  large 
ridge,  and  numerous  hummocks  rise  above  the  rest  of  the  low  ridge.  The 
course  of  the  osar  lies  obliquely  across  Shad  Pond  for  about  a  mile,  as  is 
proved  by  islands  of  gravel  rising  above  the  water.  It  soon  leaves  the 
valley  of  the  Penobscot  and  follows  the  NoUesemic  Stream  past  the  lake  of 
that  name,  and  then,  penetrating  a  low  pass,  it  extends  southward  near  the 
Seboois  River  for  many  miles.  The  ridge  is  well  developed  almost  all  the 
way.  Near  the  Piscataquis  River  it  does  not  show  above  the  marine  sedi- 
ments and  valley  drift,  and  it  has  been  either  washed  away  or  covered  out 
of  sight  by  the  clays,  or  the  gravel  may  never  have  been  deposited  in  this 
part  of  the  channel  of  the  glacial  river.  This  glacial  river  certainly  crossed 
the  Piscataquis  Valley,  for  the  gravel  ridge  begins  again  a  short  distance 
south  of  that  river  and  continues  southward  through  Edinburg  and  Argyle 
as  a  low  ridge  rising-  only  10  to  30  feet  above  the  marine  clays.  It  then 
turns  southeastward,  crosses  the  Penobscot  River  at  Olamon  Island,  and 
soon  spi'eads  out  into  broad,  rather  level,  plains  as  it  approaches  Greenfield. 

This  glacial  stream  is  pretty  long,  but,  judging-  from  the  amount  of  sedi- 


SYSTEMS  OF  GLACIAL  GEAVBLS.  117 

ment  it  deposited,  it  was  probably  not  so  large  as  the  Seboois-Medway- 
Enfield  branch.     It  drained  the  region  directly  south  of  Mount  Katahdin, 
and  it  is  an  open  question  whether  it  ought  not  to  be  known  as  the  Katah- 
din osar.     It  is  even  more  inaccessible  than  the  Enfield  branch. 
Length,  50  or  more  miles  from  Greenbush  northward. 

SOPER   BROOK    GRAVELS. 

A  ridge,  probably  of  glacial  gravel,  is  found  along  Soper  Brook,  north 
of  Ripogenus  Lake,  in  T.  4,  R.  11,  Piscataquis  County.  It  is  about  2  miles 
long,  and  is  possibly  a  branch  of  the  Katahdin  system. 

NOTE  ON  THE  UPPER  PENOBSCOT  VALLEY. 

I  have  not  had  opportunity  to  explore  this  valley  above  the  Twin 
Lakes.  On  comparing  the  map  of  the  upper  Penobscot  region  with  the 
country  lying  east  and  west  of  it,  symmetry  is  seen  to  demand  that  the 
glacial  gravels  should  extend  fai'ther  north  and  west  than  is  shown  on 
the  map.  Probably  the  osars  are  there,  but  have,  not  been  discovered  and 
reported.  The  hilly  region  about  Katahdin  can  not  be  judged  by  the  anal- 
ogy of  the  level  areas,  but  to  the  west  a  more  level  country  is  found, 
where  glacial  gravels  may  be  expected. 

EASTBROOK-SULLIVAN  SYSTEM. 

This  rather  short  system  extends  from  the  south  end  of  Webbs  Pond, 
Eastbrook,  southeastward  through  Franklin  and  Sullivan.  It  traverses  a 
rolling  plain  along  valleys  or  over  low  hills,  and  lies  wholly  within  the  area 
that  was  beneath  the  sea.  It  crosses  the  Shore  or  Telegraph  road,  and  then 
continues  southward  as  a  high,  broad  ridge  of  coarse  gravel,  cobbles,  and 
bowlderets.  At  the  east  end  of  Hog  Bay  it  turns  abrujDtly  eastward  and 
goes  up  a  narrow  valley.  It  is  said  to  continue  for  several  miles  in  this 
direction  and  to  end  near  Flanders  Pond,  in  the  northeast  part  of  Sullivan. 

MINOR   GRAVEL   SERIES. 

These  were  probably  deposited  by  different  glacial  streams. 

Amherst  delta. — A  Small,  ratlier  level-topj)ed  plain  of  sand  and  gravel  is  found 
on  the  Air  Line  road,  about  3  miles  west  of  Amherst  Post-Office,  at  the  south- 
ern base  of  a  high  range  of  granitic  hills.  Going  south  of  the  road  the 
sediments  become  finer.     The  gravel  passes  by  degrees  into  sand,  and  this 


118  GLACIAL  GRAVELS  OF  MAINE. 

into  clay,  within  one-fourth  of  a  mile.  This  clay  is  continuous  with  that 
which  extends  down  the  valley  of  Union  River  to  the  sea,  and  is  of  marine 
origin,  as  shown  by  fossils  found  about  1  mile  east  of  this  place.  North  of 
the  road  we  find  two  tributary  branches.  One  ridge  extends  for  about  one- 
eighth  of  a  mile  northwestward,  up  the  valley  of  a  small  stream;  the  other 
starts  from  a  point  a  few  rods  east  of  this  ridge  and  ascends  anothei-  valley 
northward  for  one-half  mile  or  more.  This  gravel  plain  is  small,  but  inter- 
esting. The  horizontal  transition  from  gravel  and  cobbles  on  the  north  to 
sand  and  finally  clay  on  the  south  is  shown  with  unusual  regularity  and 
within  a  short  distance.  It  is  an  instructive  instance  of  a  delta  deposited 
by  two  small  glacial  streams,  whose  mouths  were  so  near  each  other  that 
they  formed  a  single  delta-plain. 

NORTH    MARIAVILLE    SYSTEM. 

This  is  a  discontinuous  series  of  short  ridges  and  hummocks  separated 
by  numerous  short  gaps,  or  apparent  gaps.  On  the  north  the  series  begins 
about  1  mile  north  of  North  Mariaville  and  takes  a  south  course  along  the 
west  side  of  Union  River  for  several  miles.  Near  the  road  from  Otis  to 
Waltham  it  crosses  to  the  east  side  of  the  river,  where  the  gravel  takes  the 
form  of  a  low  terrace,  while  no  corresponding  terrace  is  found  on  the  west 
side  of  the  river  and  no  similar  gravel  is  in  the  bed  of  the  stream.  This  is 
thus  proved  to  be  glacial  gravel  and  not  valley  drift.  South  of  this  point 
the  valley  of  Union  River  is  a  very  level,  clay -covered  plain,  and  no  I'idges 
can  be  seen  rising  above  the  clay.     Probably  the  series  ends  near  this  place. 

WEST   MARIAVILLE   MASSIVE. 

About  1  mile  from  Union  River,  on  the  road  from  North  Mariaville 
southwestvvard  to  Tilden  Post-Office,  is  a  flattish-topped  plain  of  well- 
rounded  glacial  gravel  and  cobbles.  It  is  about  one-fourth  of  a  mile  wide 
from  east  to  west  and  three-fourths  of  a  mile  long.  The  plain  becomes 
somewhat  finer  in  composition  toward  the  south,  but  the  chang-e  is  not  so 
marked  as  it  is  in  the  case  of  most  fan-shaped  deltas.  The  plain  is  but  little, 
if  any,  broader  toward  the  south.  It  must  have  been  deposited  either  in  a 
glacial  lake  or  within  a  bay  of  the  sea  bordered  by  ice  walls  that  prevented 
the  sediment  from  spreading.  If  so,  the  outlet  channel  toward  the  sea  was 
probably  narrow. 


CLIFTON-LAMOINE  SYSTEM.  119 


PEAKED   MOUNTAIN   ESKERS. 

A  series  of  I'idges  somewhat  like  an  interrupted  osar  extends  along  the 
valley  of  a  small  stream  that  iiows  northward  ]3ast  the  western  base  of 
Peaked  Mountain,  in  the  eastern  part  of  Clifton.  The  series  seems  to  end 
in  front  of  a  rather  low  pass  leading  southeastward  through  the  high 
granitic  hills.  According  to  general  analogy,  this  small  stream  must  have 
flowed  southeast  through  the  pass,  although  it  has  not  deposited  much,  if 
any,  gravel  on  the  steep  slopes.  It  is  possible  that  its  course  lay  past  Hop- 
kins Pond  to  the  plain  in  the  western  part  of  Mariaville,  above  described. 
I  have  not  explored  the  indicated  route,  which  is  quite  inaccessible. 

CLIFTON-LAMOINE    SYSTEM. 

This  series  appears  to  begin  as  an  osar  ridge  about  one-fourth  of  a  mile 
northwest  of  Clifton  Post-Oflfice.  From  thence  it  extends  for  about  1  mile 
southeastward,  when  it  turns  neai'ly  east  and  crosses  the  granite  hills  by  a 
pass  about  80  feet  above  Clifton  (PI.  VII,  A).  This  is  the  lowest  place  in  the 
granite  range  to  be  found  in  this  vicinity.  The  gravel  is  scanty  at  the  top 
of  the  pass,  but  on  the  down  slope  soon  becomes  very  abundant  and  expands 
into  a  series  of  two  or  more  large  ridges  inclosing  kettleholes.  It  soon  turns 
nearly  south  along  the  valley  of  a  brook  past  Floods  and  Spectacle  ponds,  and 
then  in  Otis  spreads  out  into  broad  plains  from  1  to  IJ  miles  wide.  These 
extend  several  miles  southeastward  into  the  northern  part  of  Mariaville. 
These  plains  are  rather  level  on  the  top,  and  the  sediment  passes  from 
coarse  gravel  and  cobbles  on  the  north  to  horizontally  stratified  sand  on  the 
south,  which  in  turn  ends  in  the  marine  clays.  This  proves  that  the  plains 
of  Otis  are  a  delta  deposited  in  the-  open  sea.  South  of  these  plains  the 
system  becomes  discontinuous.  After  a  gap  of  somewhat  more  than  a  mile, 
a  rather  broad  ridge  of  very  round  gravel,  cobbles,  and  bowlderets  begins 
a  short  distance  northwest  of  the  tannery  in  Mariaville  and  extends  nearly 
south  for  3  miles.  Another  ridge  lies  about  1  mile  west  of  this,  situated  in 
the  southeast  part  of  Otis,  and  it  extends  farther  south  than  the  first,  so  that 
they  are  arrayed  en  dchelon.  These  ridges  are  several  hundred  feet  broad, 
with  very  gentle  side  slopes.  Two  or  three  miles  south  of  the  last-named 
ridge  is  Beach  Hill,  a  nearly  round  mound  or  massive  plain  of  glacial 
gravel,  more  than  one-fourth  of  a  mile  in  diameter,  and  rising  steeply  about 


120  GLACIAL  GRAVELS  OF  MAINE. 

75  feet  above  the  marine  clay  that  covers  its  base.  The  top  of  the  plain  is 
diversified  with  low  ridges  and  some  not  very  deep  kettleholes,  but  the  top 
is  so  level,  as  seen  from  a  distance,  as  to  resemble  one  of  the  buttes  of  the 
Rocky  Mountains.  After  a  gap  of  nearly  2  miles  a  plain  begins  on  the  east 
side  of  Union  River,  near  the  road  from  Ellsworth  to  Waltham.  This 
plain  is  from  one-fourth  to  three-fourths  of  a  mile  wide,  and,  with  two 
short  gaps,  extends  to  the  cemetery,  a  short  distance  east  of  Ellsworth, 
where  it  ends  in  a  rather  steep  bluff  on  all  sides  except  the  north.  The 
central  parts  of  the  plain,  measured  east  and  west,  contain  cobbles  and 
bowlderets;  to  the  very  south  end  of  the  plain,  but  on  the  east  and  west 
margins  pass  into  fine  gravel  and  finally  into  sand.  This  plain  thus  is  seen 
to  differ  much  from  the  typical  delta,  yet  shows  some  horizontal  assortment 
of  sediments,  as  if  the  channel  within  the  ice  was  by  degrees  enlarged  so 
much  toward  the  east  and  west  that  the  velocity  of  the  current  was  checked 
in  it — indeed,  it  practically  formed  a  lake  within  the  ice.  South  of  this  point 
there  is  another  gap  of  a  mile  or  more,  and  then  a  broad  ridge  or  plain, 
interrupted  by  a  few  short  gaps,  extends  soiithward  through  Hancock,  past 
North  Lamoine,  and  ends  not  far  above  sea  level  near  East  Lamoine,  right 
opposite  Mount  Desert  Island.  Toward  the  south  the  gravel  becomes  finer 
and  soon  passes  into  sand,  which  is  good  for  building  purposes,  and  large 
quantities  of  it  are  shipped  to  Bar  Harbor  and  along  the  coast.  The  plain 
does  not  become  fan-shaped,  but  remains  only  from  one-eighth  to  one-fourth 
of  a  mile  wide.  While,  then,  we  see  the  horizontal  classification  of  sedi- 
ments characteristic  of  the  delta,  yet  this  is  not  the  radiating  shape  of  a 
plain  deposited  in  the  open  sea,  when  it  was  free  to  spread  in  all  directions 
under  the  action  of  winds  and  tides,  as  it  would  have  been  on  the  rather 
level  plains  of  Lamoine.  These  facts  warrant  the  interpretation  that  the 
glacial  waters  were  flowing  in  a  broad  channel  which  opened  on  the  sea  and 
formed  a  sort  of  bay  or  estuary,  bordered  by  ice  walls  at  the  sides. 

Some  of  the  gaps  in  this  system  are  pretty  long,  yet  the  linear 
arrangement  of  the  several  deposits  is  such  that  there  can  be  little  doubt 
they  were  all  deposited  by  a  single  glacial  river,  with  perhaps  one  or  two 
tributary  branches.  The  largest  marine  delta  of  the  system  is  situated  in 
Otis,  above  175  feet  elevation  and  below  the  contour  of  230  feet. 

The  length  of  the  system  is  about  27  miles. 


11      BROAD   OSAR  TERRACE;    BUCKSPORT.      LOOKING    NORTH 
5  the  terrace  of  glacial  grave!,  which  is  much  obscured  by  the  marine  clay  that  c 


the  lower  slopes  of  the  hills. 


HOLDENOELAND  SYSTEM.  121 

LOCAL  ESKERS  NORTHWEST  OF  ELLSWORTH. 

Some  short  ridges  of  glacial  gravel  are  found  about  li  miles  north- 
west of  Ellsworth  Falls;  another  is  situated  on  the  line  of  the  Maine 
Central  Railroad  about  5  miles  northwest  of  Ellsworth;  and  still  another 
near  Reeds  Pond  station,  Maine  Central  Railroad. 

A  short  ridge,  ending  in  an  enlargement  at  the  south  which  resembles 
a  small  delta,  is  found  a  short  distance  southeast  of  East  Eddington.  This 
is  near  the  foot  of  the  northern  slopes  of  the  high  granite  hills  extending 
northeast  from  Orland.  The  whole  deposit  is  small,  but  I  could  find  no 
connections.  A  short  glacial  stream  probably  here  flowed  into  a  small 
lake,  perhaps  late  in  the  time  of  final  melting,  when  the  ice  next  the  hills 
was  melted,  but  some  yet  remained  over  the  open  plain  to  the  north. 

HOLDEN-ORLAND   SYSTEM. 

This  is  a  well-defined  sei'ies  of  rather  short  plains,  ridges,  and  domes 
or  mounds  of  glacial  gravel,  separated  by  gaps. 

It  appears  to  begin  near  Holden  Village,  and  extends  southwest  through 
Dedham  and  Bucksport  and  appears  to  end  not  far  north  of  Orland  Village. 
Toward  the  north  the  gaps,  though  frequent,  are  not  more  than  one-eighth 
to  one-sixth  of  a  mile  in  length.  Going  south,  we  find  the  gaps  increasing 
to  one-half  a  mile,  and  the  ridges  at  the  same  time  becoming  shorter  and 
smaller,  till  they  are  reduced  to  mere  hummocks  or  elongated  domes,  10  to 
15  feet  high. 

The  coiirse  of  this  system  is  southwest,  while  the  other  systems  of  this 
part  of  Maine  trend  south  or  southeast.  The  topographical  relations  of  the 
system  seem  to  afford  a  satisfactory  explanation  of  this  anomaly.  The 
system  lies  along  the  western  base  of  the  range  of  high  granitic  hills  before 
referred  to  as  extending  from  Orland  northeastward  across  Maine  and  New 
Brunswick.  The  schists  which  border  the  granite  on  the  west  weather 
readily,  and  it  was  not  possible  without  excavation  to  find  g'lacial  striae  in 
the  region  penetrated  by  the  gravel  system.  It  is  therefore  uncertain 
whether  there  was  a  local  deflection  of  the  ice,  caused  by  the  hills,  which 
corresponded  to  the  direction  of  the  kame  system.  This  is  a  fine  example 
of  the  discontinuous  systems  of  lenticular  or  dome-like  kames,  at  least 
toward  the  southern  end  of  the   system.     Toward  the  north  the   rido-es 


122  GLACIAL  GEAVELS  OF  MAINE. 

become  longer  and  approach  the  short  osar  type,  and  are  sometimes  broad, 
like  osar-plains.  It  should  be  noted  that  in  the  discontinuous  systems  as 
here  defined  the  gaps  are  not  due  to  erosion  subsequent  to  the  deposition  of 
the  o-ravel,  and  they  are  as  constant  and  noticeable  a  feature  as  the  gravels 
themselves.  As  a  class  they  are  quite  nearlj^  parallel  with  the  movements 
of  the  ice  during  the  last  of  the  Glacial  period.  This  makes  it  probable 
that  there  was  a  movement  of  the  ice  southwest  into  Penobscot  Bay  about 
12  miles  along  the  western  bases  of  the  granite  hills;  but  thus  far  it  is  not 
proved  by  evidence  of  the  scratches. 

MOOSEHEAD  LAKE  SYSTEM. 

The  principal  branches  of  this  important  system  were  remarkable  for 
being  very  widely  separated  at  the  north.  They  drained  the  glacial  waters 
of  a  large  part  of  the  Penobscot  Valley  and  its  tiibutaries,  and  poured 
them  into  the  Penobscot  Bay  by  a  single  channel.  Estimating  the  amount 
of  water  by  the  area  drained,  only  three  or  four  of  the  osar  rivers  of  the 
State  probably  equaled  this  river  in  volume,  yet  a  dozen  or  more  of  them 
exceed  this  in  the  quantity  of  sediment  they  have  deposited.  With  insig- 
nificant exceptions,  the  system  traverses  a  region  of  slates  and  schists,  and 
it  is  the  universal  law  that  when  an  osar  river  passed  through  a  granite 
region  its  gravels  are  many  times  as  abundant  as  those  of  rivers  in  slate 
regions  having  the  same  length.  The  tributaries  of  this  system  are  all 
easily  traced;  they  left  ridges  nearly  as  large  as  those  of  the  main  river. 
The  longest  one  of  these  is  the  Medford-Hampden  osar. 

3IEDF0RD -HAMPDEN   OSAR. 

On  the  north  it  appears  to  begin  as  a  series  of  ridges  on  the  south 
shore  of  South  Twin  Lake.  It  passes  southward  as  a  single  two-sided 
ridge.  In  crossing  Seboois  Lake  it  is  said  to  appear  at  certain  places  as 
"horseback  islands,"  and  farther  south  it  crosses  the  valley  of  Schotaza 
Creek  obliquely.  The  above  statements  are  made  on  the  authority  of  Mr. 
Eber  Ames,  of  Medford,  and  are  confirmed  by  many  others.  From  near 
Schotaza  Creek  I  have  followed  the  system  all  the  way  to  Hampden.  For 
several  miles  north  of  the  Piscataquis  River  it  is  a  ridge  20  to  40  feet  high, 
with  arched  cross  section  and  broad  base.  The  gravel  contained  many 
cobbles  and  some  bowlderets,  all  well  rounded,  which  proves  that  the  ridge 


MEDFORD-HAMPDEN  OSAR. 


123 


extends  a  considerable  distance  north  of  Schotaza  Creek.  It  reaches  the 
Piscataquis  River  at  the  mouth  of  Schoodic  Stream  in  Medford.  The  gen- 
eral course  of  the  Piscataquis  is  east,  but  in  Medford  it  bends  sharply  to 
the  north  for  more  than  a  mile  and  then  resumes  its  eastward  course.  The 
osar  reaches  the  river  just  where  it  makes  this  last  bend  eastward  and  fol- 
lows the  Avestern  bank  for  about  1  mile,  and  then  crosses  the  river.  The 
river  in  its  eastward  course  impinges  against  the  base  of  the  osar  and  is 
deflected  by  it  nearly  one-fourth  of  a  mile  northward  before  cutting  through 


/■ 


Fia.  10.— Osar  cut  by  the  I'iscataquia  Kiver  at  Medluid  Ferry. 

it.  The  ridge  is  here  from  20  to  30  feet  high,  and  is  in  part  covered  by  the 
sedimentary  sand  and  clay  which  constitute  the  valley  alluvium.  This 
place  is  not  far  from  the  tipper  limit  of  the  sea.  Medford  Ferry  is  situated 
just  at  the  point  where  the  Piscataquis  breaks  through  the  osar  (see  fig.  10). 
From  this  point  southward  the  road  to  Medford  Center  follows  the  ridge  for 
a  short  distance  and  then  passes  east  of  it.  The  osar  extends  about  one- 
fourth  of  a  mile  west  of  Medford  Center  and,  still  rising  above  the  Piscata- 
quis River,  it  penetrates  a  low  pass  in  Medford  and  Lagrange.  It  is  here 
somewhat  discontinuous,  and  in  places  takes  the  form  of  the  osar-plain. 


124  GLAOIAL  GRAVELS  OF  MAINE. 

especially  for  some  miles  soutli  of  the  divide.  In  an  excavation  between 
Medford  and  Lagrange,  bowlderets  and  bowlders  2  to  3  feet  in  diameter,  all 
well  rounded  and  polished,  were  abundant  as  far  down  as  the  excavation 
reached — 6  to  8  feet.  The  osar  passes  about  half  a  mile  east  of  Lagrange 
station.  A  short  distance  south  of  this  point  the  Bangor  and  Aroostook  Eail- 
road  comes  near  the  ridge,  and  for  several  miles  in  Lagrange  and  Alton  it  is 
constructed  along  the  base  of  the  osar.  A  wagon  road  is  laid  out  on  the  top 
of  tlie  osar  for  many  miles.  In  this  part  of  its  course  it  is  a  broad  ridge  or 
narrow  plain  with  gentle  lateral  slopes  and  arched  cross  section,  rising  10  to 
30  feet  above  a  very  level  plain  of  marine  clay.  Both  the  clay  and  the  ridge 
are  sprinkled  with  floe  bowlders.  At  Pea  Cove,  Alton,  the  ridge  becomes 
narrower,  and  has  steeper  lateral  slopes  from  this  point  southward  through 
Oldtown  and  Orono,  on  the  west  side  of  the  Penobscot.  In  Veazie  the 
ridge  begins  to  be  interrupted  by  short  gaps.  These  gaps  are  especially 
noticeable  south  of  Mount  Hope  Cemetery,  situated  not  far  north  of  Bangor. 
Mount  Hope  itself  is  a  part  of  this  gravel  system.  The  next  gravel  of  the 
series  is  on  the  east  side  of  the  Penobscot  River  in  Brewer,  just  above  the 
railroad  bridge,  Bangor.  The  next  gravel  is  the  ridge  at  ^vhat  is  known  as 
High  Cut,  whei-e  the  Maine  Central  Railroad  cuts  through  an  elongated 
dome  of  this  series  in  the  southeastern  part  of  Bangor.  In  like  manner,  a 
series  of  short  and  broad  ridges,  separated  by  intervals  of  one-fourth  mile 
to  more  than  1  mile,  extends  along  the  west  side  of  the  Penobscot  River 
through  Hampden  and  joins  the  main  system  not  far  west  of  Ball  Hill 
Cove,  near  the  north  line  of  Winterport. 

A  study  of  the  glacial  gravel  and  of  the  drift  of  the  Penobscot  Valley 
will  show  the  great  difference  between  glacial  and  river  gravels  in  Maine. 

The  course  of  this  osar  is  wholly  within  a  gently  rolling  plain,  much 
of  which  is  as  level  as  the  prairies.  The  base  of  the  ridge  is  more  or  less 
covered  with  clay  containing  marine  fossils  as  far  north  as  Alton,  and  pei'- 
haps  farther.  Sedimentary  clay  is  found  in  places  along  the  top  of  the 
pass  in  the  northern  part  of  Lagrange.  If  this  Avere  marine  clay  we  might 
expect  a  marine  delta  in  the  valley  of  the  Piscataquis  a  few  miles  north- 
ward. There  is  no  such  delta,  and  the  history  of  the  Medford-Lagrange 
pass  seems  to  be  this :  First,  in  a  rather  broad  channel  within  the  ice,  an 
osar-plain  was  deposited.  Subsequently  the  channel,  by  lateral  melting, 
became  still  broader,  and  the  supply  of  water  was  no  longer  able  to  main- 


MOOSEHEAD  LAKE  OSAR.  125 

tain  a  swift  current  in  the  broader  channel.  Clay  was  then  laid  down  on 
the  flanks  of  the  previously  formed  osar-plain — osar  border  clay. 

In  places  the  sea  waves  have  washed  down  some  of  the  top  of  the  osar 
and  strewn  the  gravel  over  the  adjoining  clay.  This  osar  is  nowhere  very 
high,  and  it  does  not  spread  out  into  broad  plains,  like  many  of  the 
systems,  yet  it  is  so  continuous  north  of  Veazie  that  it  contains  a  large 
amount  of  gravel.  The  meanderings  of  this  osar  do  not  in  g'eneral  depend 
on  any  very  evident  surface  features  of  the  land. 

Its  length  is  about  60  miles,  from  Hampden  .north. 

MOOSEHEAD    LAKE    OSAR. 

This  appears  to  be  the  longest  tributary  of  the  system.  It  is  uncer- 
tain how  far  a  ridge  of  glacial  gravel  extends  in  the  floor  of  Moosehead 
Lake.  Gravel,  probably  glacial,  appears  on  Hogback  and  Sandbar  islands 
in  the  midst  of  the  lake.  An  osar  appears  on  the  western  shore  about  3 
miles  north  of  the  so-called  Southwest  Cove  of  the  lake.  It  follows  the 
west  shore  to  the  foot  of  the  lake  in  Greenville,  and  thence  runs  southward 
in  a  nearly  straight  course  over  a  low  divide  in  Shirley.  From  Shirley 
northward  the  ridge  is  quite  continuous,  but  while  following  the  Piscataquis 
Valley  in  Blanchard  and  Abbott  on  a  down  slope  of  about  50  feet  per  mile 
the  gravel  is  much  interrupted  for  several  miles,  partly  by  recent  erosion. 
Near  the  north  line  of  Abbott  a  plain  of  sand  and  gravel,  now  much  eroded, 
appeal's  in  the  midst  of  the  valley.  A  two-sided  ridge  extends  for  some 
distance  near  Upper  Abbott,  but  its  sunnnit  has  nearly  the  same  level  as 
terraces  which  border  both  sides  of  the  valley.  This  appears  to  be  a  ridge 
of  erosion,  though  it  may  have  along  its  axis  a  core  of  coarser  matter  than 
is  contained  in  most  of  the  plain.  The  stones  of  the  ridge  and  terraces  are 
well  rounded,  like  those  of  the  glacial  gravels,  but,  on  the  other  hand,  the 
gravel  extends  from  side  to  side  of  the  valley,  like  river  alluvium.  This 
condition  prevails  for  several  miles  in  Abbott.  Much  of  this  sand  and 
gravel  is  glacial,  but  the  broad  alluvial  ridges  and  terraces  of  the  Piscataquis 
Valley  in  Abbott  present  a  complex  problem.  Part  of  it  seems  to  be  an 
osar-plain,  part  is  a  frontal  delta,  part  of  it  may  have  been  deposited  in  a 
glacial  lake,  and  in  part  it  is  composed  of  river  drift.  The  very  round 
shapes  of  the  stones  of  what  appears  to  be  valley  drift  may  best  be 
accounted  for  as  an  incident  in  the  final  meltins-  and  retreat  of  the  ice.     If 


126  GLACIAL  GKAVELS  OF  MAINE. 

the  ice  still  remained  over  the  Moosehead  region  to  the  north,  the  glacial 
streams  would  bring  down  well-polished  sediment,  while,  when  the  ice  had 
melted  over  the  Piscataquis  Valley,  this  rounded  sediment,  as  it  was  poured 
out  by  the  glacial  streams  on  the  steep  slopes  in  Blanchard,  would  be 
transported  b}"  the  swift  Piscataquis  River  and  deposited  on  the  more  gentle 
slopes  in  Abbott.  In  this  way  we  may  account  for  valley  drift  containing 
stones  having  the  shapes  of  the  glacial  gravels.  Of  course  the  stones  would 
be  somewhat  rounded  while  being  transported  by  the  river,  but  these  stones 
are  rounder  than  I  find  in  the  beds  of  even  the  swift  streams  that  come 
down  from  ilouut  Katahdin.  "With  respect  tii  the  ice  they  were  frontal 
matter. 

From  Abbott  a  line  of  ridges  and  terraces  of  unmistakable  glacial 
gravel,  interrupted  by  several  short  g'aps,  is  found  on  the  south  side  of  the 
Piscataquis  Rivei-,  extending  eastward  through  Guilford  and  Sangerville. 
It  then  turns  southeastward  and  follows  the  valley  of  Black  Brook  (a 
stream  flowing  northwest  into  the  Piscataquis  River)  past  Dover  South 
Mills  to  the  "Notch"  in  the  northeastern  part  of  Grarland.  All  the  way 
from  Abbott  to  the  Notch  the  ridges  are  in  general  broad  and  plain-like, 
some  of  them  50  and  even  70  feet  high,  and  are  separated  by  frequent 
gaps.  Near  Dover  South  Mills  there  are  two  parallel  ridges  for  nearly  a 
half  mile,  which  inclose  a  deep  elongated  basin.  This  enlargement  of  the 
system  about  two-thirds  of  the  distance  up  the  slope  closel}'  corresponds 
to  the  plexus  of  reticulated  ridges  in  Prentiss,  also  on  a  northward  slope. 

The  Notch  is  a  remarkably  low  pass  which  forms  a  natural  gateway 
through  the  range  of  rather  high  hills  which  border  the  Piscataquis  Valley 
on  the  south.  The  top  of  the  pass  is  less  than  100  feet  above  the  Piscata- 
quis River  at  the  mouth  of  Black  Brook.  Approaching  the  Notch  from  the 
northwest,  man}-  ridges  and  irregular  terraces  and  mounds  of  glacial  sand 
and  g-ravel  are  seen  along  the  south  flanks  of  the  main  ridge.  Part,  if  not 
all,  of  these  are  due  to  irregular  erosion,  by  springs  and  streams,  of  a  plain 
of  rather  fine  sand  and  gravel  which  was  laid  down  at  the  side  of  the  main 
ridge  of  coarse  gravel  and  cobbles.  As  a  whole,  this  plain  appears  to  cor- 
respond to  Avhat  I  have  termed  the  broad  osar.  In  this  case  an  osar  was 
first  formed.  Subsequently  the  channel  became  enlarged,  not  on  both 
sides,  as  usually  happens,  but  almost  wholly  at  the  south  side — the  side 
away  from  the  glacial  flow.     In  this  broad  channel  was  deposited  a  plain  of 


MOOSEHBAD  LAKE  OSAR.  127 

finer  sediment  which  was  more  nearly  horizontally  stratified  than  the  coarse 
gravel  of  the  ridge  formed  in  the  narrow  channel. 

There  is  much  silt  and  clay  covering  the  upper  part  of  the  valley  of 
Black  Brook  I  have  no  acciu-ate  data  as  to  the  difference  of  level  between 
the  Notch  and  the  Piscataquis  River.  By  measurements  with  the  aneroid, 
taken  at  several  hours'  interval,  the  difference  is  but  little  short  of  100  feet. 
If  so,  the  clay  of  the  valley  ol  Black  Brook  near  the  Notch  is  not  due  to 
the  floods  of  the  Piscataquis,  being  higher  than  the  terraces  of  that  river. 
Besides,  these  clays  are  so  abundant  that  it  seems  improbable  that  so  large 
an  amount  of  sediment  could  be  carried  several  miles  along  a  backwater 
lake.  A  much  more  probable  theorj^  is  that  the  clays  were  deposited  late 
in  the  Ice  period,  wlien  the  broad  channel  of  the  osar-plain  had  become 
still  further  broadened  and  the  ice  next  the  hills  had  melted,  so  that  the 
valley  of  Black  Brook  formed  a  lake  between  the  hills  on  the  southeast  and 
the  ice  which  still  covered  the  valleys  of  Black  Brook  and  the  Piscataquis 
River  to  the  northwest.  This  lake  would  for  a  time  overflow  southward 
through  the  Notch,  and  would  cease  to  be  a  lake  when  the  ice  over  the 
Piscataquis  Valley  had  melted  so  that  the  waters  could  escape  along  the 
present  lines  of  drainage.  Into  this  lake  considerable  mud  would  for  a 
time  be  brought  by  glacial  sti-eams. 

Just  at  the  north  end  of  the  Notch  the  gravel  system  is  joined  by  a 
tributary  branch.  It  appeared  to  be  short.  I  traced  it  for  one-fourth  of  a 
mile,  when  it  seemed  to  end.  I  afterwards  regretted  that  I  did  not  explore 
the  country  to  the  north,  as  it  is  possible  a  discontinuous  series  of  kames 
may  extend  in  that  direction.  The  osar-plain  is  fully  one-eighth  of  a  mile 
broad  at  the  north  end  of  the  Notch,  and  extends  southward  abo+it  one-half 
mile.  Then  for  another  half  mile,  where  the  steep  hillsides  almost  meet  at 
the  bottom  so  as  to  form  a  V-shaped  valley,  a  few  very  round  cobbles  and 
bowlderets  are  found  here  and  there  and  testify  that  the  osar  river  flowed 
through  the  Notch.  The  force  of  current  must  have  been  verj^  great  in 
order  to  leave  so  little  gravel  in  the  valley.  Bare  ledges  abound,  yet  here 
and  there  considerable  areas  of  till  have  escaped  denudation.  The  till  was 
the  fine  clayey  till  characteristic  of  the  slate  regioias.  The  rounded  osar 
stones  distinctly  overlie  the  till,  and  therefore  must  have  been  deposited  at 
a  later  stage.  I  made  no  excavations,  and  do  not  know  with  certainty  that 
there  are  no  rounded  osar  stones  mixed  with  the  till,  but  in  the  banks  of  a 


128  GLACIAL  GRAVELS  OP  MAINE. 

small  brook  no  such  stones  appeared  as  part  of  the  till.  There  is  here  no 
proof  of  a  landslide  of  till  from  the  hillsides,  and  no  proof  that  till  dropped 
down  into  a  subglacial  tunnel  from  above  subsequent  to  the  deposition  of 
the  glacial  gravel.  The  evidence  strongly  favors  the  following  conclusions : 
(1)  The  till  was  first  (in  order  of  time)  deposited  beneath  the  ice  as  a  ground 
moraine.  (2)  Subsequently  part  of  this  till  was  washed  away  by  the  glacial 
river.  (3)  The  fact  that  a  considerable  part  of  the  till  escaped  denudation, 
notwithstanding  the  large  size  of  this  glacial  river,  proves  that  it  must  have 
presented  considerable  resistance  to  erosion;  and  this  conclusion  follows 
whether  we  consider  that  the  osar  river  flowed  in  a  subglacial  tunnel  or  in 
an  ice  canyon  open  to  the  air.  (4)  The  fact,  then,  that  the  glacial  gravels 
often  overlie  uneroded  till  is  not  fatal  to  the  theory  that  the  kames  and 
osars  were  deposited  in  subglacial  tunnels.  The  fact  is,  the  ground  moraine 
was  a  very  tough,  compact  mass,  and  not  easily  eroded  even  by  a  rapid 
glacial  stream.  Besides,  it  is  not  proved  that  in  all  cases  subglacial  streams 
Avould  erode  the  till  while  those  flowing  in  supei"ficial  channels  would  not. 
(5)  The  absence  of  till  overlying  the  osar  leaves  us  without  direct  proof  that 
the  osar  river  here  flowed  in  a  subglacial  tunnel. 

At  the  south  end  of  the  Notch  the  gravel  and  cobbles  spread  out  into 
a  fan-shaped  plain  about  one-half  mile  long  and  half  as  broad.  The  plain 
has  been  eroded  by  a  small  stream  which  flows  southward  through  its  cen- 
ter, so  that  the  plain  of  original  deposition  has  been  cut  into  two  parallel 
terraces  separated  by  a  valley  of  erosion.  The  lateral  terraces  are  also 
intersected  by  several  transverse  valleys  of  erosion,  so  that  what  must  have 
been  originally  a  continuous  plain  is  now  a  series  of  detached  terraces  and 
mounds.  The  gravel  is  coarse  at  the  north  end  of  the  plain  and  grows 
much  finer  toward  the  south.  It  was  a  small  delta,  deposited  either  in  a 
glacial  lake  or  in  the  sea.  The  plain  is  bordered  by  clay,  and  a  sheet  of 
clay  extends  from  this  point  all  the  way  to  the  sea.  I  found  marine  fossils 
in  this  clay  at  Kenduskeag  Village,  a  few  miles  south  of  this  place.  It  is 
certain  that  the  sea  extended  nearly  to  the  Notch,  but  exactly  liow  far  I 
have  not  been  able  to  determine.  If  the  clays  that  border  the  osar  all  the 
way  from  the  Notch  southward  are  not  wholly  marine,  then  we  must  regard 
them  as  osar  border  clays  toward  the  north,  i.  e.,  deposited  in  the  broad- 
ened osar  channel  at  the  sides  of  the  pi-eviously  deposited  glacial  gravel. 

South  of  the  gravel  plain  at  the  south  end  of  the  Notch  there  is  an 


MOOSEHEAD  LAKE  OSAR.  129 

apparent  gap  in  the  gravels  of  somewhat  more  than  a  mile.  In  Charleston, 
not  far  north  of  the  Corinth  line,  a  ridge  rises  above  the  clay.  It  is  low 
and  has  gentle  side  slopes.  It  extends  southeastward  for  several  miles, 
passing  about  one-half  mile  west  of  East  Corinth,  here  becoming  higher 
and  narrower  and  with  steeper  sides.  Near  here  many  boiling  springs 
issue  from  the  base  of  the  ridge.  The  ridge  is  bordered  on  each  side  and 
partly  covered  to  a  height  of  10  or  more  feet  by  sedimentary  clay.  The 
gravel  is  readily  permeated  by  the  rains,  but  the  water  can  not  readily 
escape  from  the  sides  of  the  ridge  on  account  of  the  rather  impervious 
clay.  In  this  natural  channel  it  runs  lengthwise  of  the  ridge.  Coming  to 
the  lower  grounds,  it  fills  up  the  gravel  to  the  top  of  the  clay  and  boils 
over  the  top  or  escapes  through  the  clay  near  the  gravel.  In  the  lowlands 
wells  dug  in  the  gravel  ridge  reach  water,  but  the  uplands  are  so  dry  that 
the  winds  circulate  freely  through  the  gravel  and  cobbles.  The  cellars  of 
houses  built  on  the  gravel  in  such  situations  are  exposed  to  rapid  currents 
of  air  in  time  of  high  winds,  and  have  to  be  cemented  tight  before  the 
houses  are  habitable.  In  various  parts  of  the  State  great  numbers  of  wells 
have  been  dug  in  the  glacial  gravels  in  such  situations  that  it  was  inevitable 
that  all  the  sui'face  water  would  be  at  once  conducted  away  to  lower  levels, 
and  where  it  would  be  impossible  to  get  water  without  penetrating  the 
gravel  into  the  underlying  till,  and  the  loose  gravel  generally  caved  in 
before  this  depth  could  be  reached. 

In  Corinth  the  osar  and  the  neighboring  clay  are  in  a  few  places 
sprinkled  with  bowlders  having  till  shapes,  probably  dropped  by  ice  floes. 
The  ridge  is  for  several  miles  parallel  with  the  Kenduskeag  River.  Near 
the  south  line  of  Corinth  the  osar  crosses  the  Kenduskeag  as  a  shallow 
bar  extending  across  the  stream.  The  water  plunging  over  the  bar  has 
eroded  a  deep  hole  directly  below  it,  known  as  the  "Salmon  hole."  In 
general,  if  the  explorer  of  glacial  gravel  hears  of  a  salmon  hole  on  an 
east-and-west  stream,  he  may  at  once  suspect  it  is  forraed  where  a  stream 
flows  over  a  submerged  osar.  The  osar  now  turns  southwesterly  and  soon 
disappears  on  the  surface,  yet  can  be  readily  traced  for  about  a  mile  beneath 
the  marine  clay.  By  inquiries  concerning  the  nature  of  the  soil  found  in 
digging  wells,  it  is  often  possible  to  trace  an  osar  which  is  deeply  hidden 
beneath  the  clay,  or  perhaps  may  show  as  a  low  momid  covered  by  clay. 
As  a  typical  instance,  and  in  order  to  fully  explain  the  methods  employed 
3ION  xxxiv 9 


130  GLACIAL  GRAVELS  OF  MAINE. 

in  this  investigation,  I  give  a  single  observation  made  about  a  half  mile 
south  of  where  the  osar  crosses  the  Kenduskeag  River 

The  surface  was  wholly  covered  by  clay  and  silty  clay.  A  well  had 
been  dug  200  feet  or  more  in  front  of  a  house.  This  was  an  unusual 
position  and  required  investigation.  Inquiry  showed  that  two  or  three  wells 
had  been  dug  near  the  house,  all  penetrating  3  or  4  feet  of  clay,  and, 
deeper,  diy  gravel  and  cobbles,  until  the  wells  caved  in.  One  of  these 
wells  was  80  feet  in  depth.  Afterwards  a  well  was  dug  a  few  rods  back  of 
the  house,  reaching  water  at  the  depth  of  15  feet  in  clay,  and  the  same 
experience  was  had  when  the  Avell  in  front  of  the  house  was  dug.  The 
house  was  situated  right  on  the  line  of  the  buried  osar  prolonged.  Hence 
it  was  evident  that  the  osar  had  disappeared  simply  because  it  had  been 
flanked  and  covered  b}^  80  or  more  feet  of  cla}'. 

With  a  few  short  gaps,  where  it  may  exist,  but,  if  so,  is  covered  b}'  the 
marine  clay,  the  osar  continues  southwestward  over  a  rolling  country. 
Two  miles  north  of  Hermon  Pond  it  spreads  out  into  a  hill  or  table-like 
plain,  varying  from  one-fourth  to  one-half  mile  wide  and  more  than  1  mile 
long,  rising  50  feet  above  the  marine  clay  that  covers  its  base.  The  surface 
is  rolling  and  incloses  shallow  basins.  Although  not  large  as  compared 
with  the  plains  of  many  of  the  gravel  systems,  unless  we  except  the  plains 
in  Abbott,  these  are  probably  the  largest  plains  in  the  Avhole  line  of  the 
system.  They  are  not  true  delta-plains,  ending  in  sand  and  clay.  After  a 
short  apparent  gap  the  ridge  begins  again  and  extends  past  Hermon  Pond 
station  to  the  north  shore  of  Hermon  Pond.  The  ridge  is  cut  through  b}' 
the  Maine  Central  Railroad  just  at  the  station,  being  there  covered  by 
marine  clay,  and  a  short  distance  south  of  that  point  the  gravel  has  been 
extensively  excavated  by  the  railroad  company.  The  gravel  reappears  on 
the.  south  shore  of  Hermon  Pond  and  passes  a  short  distance  east  of  West 
Hampden.  From  this  point  southward  the  gaps  becorhe  a  constant  and 
essential  feature  of  the  s}'stem.  South  of  here  the  ridges  are  nowhere  more 
than  1  or  2  miles  long,  and  often  they  are  so  short  and  broad  that  they  may 
be  called  plains  or  domes  rather  than  ridges.  These  discontinuous  gravels 
extend  in  nearly  a  straight  line  from  West  Hampden  to  Winterport  Village, 
passing  nearly  1  mile  west  of  Ball  Hill  Cove,  near  which  point  it  unites 
with  the  Medford-Hampden  branch.  The  gravel  appears  at  the  cemetery, 
Winterport,  and  at  various  gravel  pits  in  the  southern  part  of  that  village 


f 

,4 


KEIvTDUSKE AG-HAMPDEN  BRANCH.  131 

it  is  overlain  by  clay.  Within  a  mile  south  of  the  village  the  system  comes 
obliquely  down  to  the  shore  of  the  Penobscot  River,  and  its  course  lies 
within  a  broad  bay  of  the  Penobscot  River  from  this  point  to  Frankfort 
Village.  It  then  follows  the  valley  of  Marsh  River  past  the  bases  of  the 
high  granitic  hills  which  cluster  about  Mosquito  Mountain.  From  this  point 
southward  the  gravel  contains  a  large  proportion  of  granite  and  the  ridges 
become  more  nearly  continuous.  Numerous  bowlderets  appear,  and 
bowlders  up  to  4  feet  in  diameter.  These  in  part  have  till  shapes  and  are 
floe-bowlders,  but  many  of  them  are  water-rounded  and  polished  on  their 
unweathered  surfaces,  and  are  therefore  an  integral  part  of  the  osar.  The 
great  size  and  number  of  these  large  rounded  bowlders  favor  the  hypothesis 
that  they  were  deposited  in  a  subglacial  channel.  The  system  passes 
through  Prospect  Post-Office,  and  then  soon  turns  southeast  along  the 
northern  slopes  of  a  range  of  hills.  It  comes  nearly  to  Gondola  Cove,  and 
then  turns  southward  parallel  with  the  Penobscot  Bay.  As  a  broad  ridge 
it  comes  down  to  the  shore  of  the  bay  at  Sandy  Point,  Stockton,  where  it 
ends  in  a  cliff  of  erosion  at  the  beach.  The  bluff  here  is  near  25  feet  high. 
Gravel  is  reported  at  Fort  Point,  in  the  line  of  this  ridge  prolonged.  I  have 
examined  the  deposit  and  am  in  doubt  whether  it  is  glacial  gravel  or  a 
raised  beach. 

Its  length  from  Moosehead  Lake  to  Penobscot  Bay  is  about  80  miles. 

KENDUSKEAG-HAMPDEN   BRANCH. 

This  begins  not  far  north  of  the  south  line  of  Charleston  and  extends 
southward  through  the  eastern  part  of  Corinth,  then  southeasterly  to  Ken- 
duskeag  Village,  where  it  abruptly  turns  southwest  to  Levant  Village.  It 
here  turns  south,  and  is  interrupted  by  numerous  gaps  from  this  point  on. 
It  crosses  a  low  col,  and  at  the  southern  end  of  the  pass  it  makes  a  sharp 
meander  almost  west  for  one-fourth  of  a  mile,  and  then  as  abruptly  turns 
southward  again.  The  system  crosses  Hermon  Bog  and  the  Maine  Central 
Railroad  a  short  distance  east  of  Hermon  station.  A  continuous  ridge 
extends  from  the  railroad  for  about  2  miles,  where  the  system  becomes  inter- 
rupted by  rather  long  gaps  again.  This  glacial  river  may  have  joined  the 
Medford  branch  near  Hampden  Upper  Corner,  but  my  most  recent  informa- 
tion makes  it  more  probable  that  it  joined  the  main  osar  river  near  the  south 
line  of  Hampden,  and  that  its  course  lies  a  mile  or  more  west  from  the 
Penobscot.     I  have  not  personally  explored  this  series  in  Hampden. 


132 


GLACIAL  GKAVELS  OF  MAINE. 


ii     11      Sect  on  ot    sar    Jjuviiit 


This  osar  is  a  ridge  from  10  to  50  feet  high,  and  north  of  Levant  it 
has  rather  steep  lateral  slopes  (see  fig.  11).  It  nowhere  expands  into  broad 
plains,  though  it  is  somewhat  plain-like  south  of  the  railroad  in  Hermon.     It 

begins  a    few    miles    south    of 
the    high    hills    bordering   the 
Piscataquis  Valley  on  the  south. 
Except  near  its  north  end  the 
series  lies  wholly  in  a  region 
that    was   under   the   sea.     At 
Kenduskeag  Village  the  lines  of  stratification  of  the  ridge  are  much  dis- 
torted, as  shown  in  figs.  12  and  13. 
Its  length  is  about  25  miles. 

EXETER   MILLS-CARMEL   BRANCH. 

This  branch  appears  to  begin  near  the  northern  brow  of  a  hill  about  1 
mile  south  of  Exeter  Mills  and  at  an  elevation  of  about  100  feet  above  that 
place.  The  series  for  sev- 
eral miles  is  interrupted 
by  numerous  short  gaps, 
yet  is  easily  traceable  to    p,,^.j,_^.^„,^,^i,, ,,,,,,,_,,„„„ „,_.„,  K,.n,i„.k,.,,.    A,„iay,.,-sare 

South    Levant    and    thence  crumpled  as  sho«u  m  ag.  la,  thcU,j»ii<  cuutam.  muck  day  ananu... and. 

through  the  eastern  part  of  Carmel  to  join  the  Moosehead  Lake  osar  some- 
what more  than  a  mile  north  of  Hermon  Pond  station  (see  fig.  14).  It  is 
nowhere  a  very  large  ridge,  being  10  to  30  feet  high.  In  Carmel  it  shows 
several  remarkable  zigzags  (see  fig.  15).  It  has  been  under  the  sea  for 
most  of  its  com-se,  and  is  often  nearly  covered  on  its  flanks  by  marine  clay. 


ria.  13.— Crumpled  ttrit 


flg.  12. 


In  several  places  it  develops  into  cones  considerably  higher  than  the  rest 
of  the  ridge.  In  one  place  it  expands  laterally  and  incloses  a  deep  kettle- 
hole,  and  right  south  of  this  point  is  a  cone  of  unusual  height.  It  nowhere 
expands  in  broad  plains.     On  the  north  it  begins  on  the  south  side  of  the 


MOOSEHEAD  LAKE  SYSTEM. 


133 


valley  of  the  Keiiduskeag  and  several  miles  south  of  the  high  hills  lying 
south  of  the  Piscataquis  River.  It  traverses  a  gently  rolling  plain.  Its 
length  is  about  12  miles 
from  Hermon  Pond 
north. 

The  following- 
named  osars  are  situ- 
ated between  the  two 
principal  branches  of 
the  Moosehead  Lake- 
Penobscot  Bay  system. 
The  streams  which 
drained  this  portion  of 
the  ice-sheet  would  naturally  flow  into  the  system,  but  it  may  have  been  at 
a  time  before  the  deposition  of  these  glacial  gravels.  I  have  not  yet  been 
able  to  make  out  any  connection  between  these  and  the  Penobscot  Bay  sys- 


PlG.  14. — Section  across  Exeter  Mills-Hermon  osar,  in  Carmel. 


Fl      lo  — Me  nler  n„  ofosar    C  rmel      The  fenc    l    }      It  along  the  top  of  the  ndg 

tem.  It  is  probable  that  the  osars  next  to  be  named  were  deposited  at  a  time 
when  the  ice  had  receded  to  the  north  of  the  Piscataquis  River,  and  that 
therefore  they  are  independent  systems  deposited  late  in  the  Ice  period. 


134  GLACIAL  GRAVELS  OF  MAINE. 

JO  MERRY  OSAR. 

This  osar  is  said  to  extend  throiigli  the  wilderness  for  about  10  miles 
along  Pratt  Brook,  a  stream  which  flows  nearly  east  into  the  middle  of  Jo 
Merry  (or  Jo  Mary)  Lake.  Its  course  prolonged  would  lead  it  near  South 
Twin  Lake,  and  it  may  be  an  extension  of  the  Medford-Hampden  osar. 

ROACH  RIVER  OSAR. 

Roach  River  flows  westward  into  Moosehead  Lake.  An  osar  follows 
the  valley  of  this  stream  quite  continuously  for  about  12  miles.  Large 
pebbles  and  cobbles,  with  some  bowlderets,  make  up  the  larger  part  of  the 
ridge.  The  stones  are  not  much  rounded  at  the  angles,  though  they  plainly 
have  polished  surfaces,  an  indication  that  the  system  does  not  extend  much 
farther  to  the  north  or  west.  From  the  head  waters  of  Roach  River  low 
passes  lead  down  the  valleys  of  both  the  east  and  the  middle  branches  of 
Pleasant  River.  These  two  branches  unite  near  the  north  line  of  Brown- 
ville,  and  from  near  their  junction  a  plain  of  sand  and  gravel  containing 
many  very  round  pebbles  and  cobbles  extends  up  both  valleys  for  about 
3  miles  northward.  Here  my  exploration  ended,  and  my  information  as  to 
the  valleys  above  this  point  is  indefinite  and  conflicting.  The  preponder- 
ance of  evidence  favors  the  hypothesis  that  the  principal  glacial  streams 
flowed  down  the  valley  of  the  east  branch  of  Pleasant  River.  It  length  is 
about  25  miles. 

KATAHDIN   IRON   WORKS   OSAR. 

A  two-sided  ridge  from  15  to  30  feet  high  extends  along  the  valley  of 
the  west  branch  of  Pleasant  River  for  several  miles  above  the  Katahdin 
Iron  Works.  Much  well-rounded  gravel  is  found  along  the  valley  below 
this  place  in  Williamsburg  which  resembles  a  delta  in  composition  and 
structure.  The  most  probable  theory  as  to  its  origin,  according  to  my 
present  information,  is  that  glacial  rivers  flowed  down  the  valleys  of  all 
three  branches  of  the  Pleasant  River  at  a  time  when  the  valley  of  the  main 
river  to  the  south  Avas  bare  of  ice.  The  well-rounded  gravel  was  thus 
brought  down  to  the  extremity  of  the  ice  and  then  spread  as  vallej^  drift 
over  the  open  valleys.  This  is  an  interesting  region  and  deserves  further 
study. 

A  plain  of  well-rounded  gravel  more  than  2  miles  long  and  from  one- 


SYSTExMS  OF  GLACIAL  GEAVELS.  135 

fourth  to  one-half  mile  wide  is  found  on  the  west  side  of  Pleasant  River  a 
short  distance  east  of  Milo  Village.  A  line  of  clay  covers  the  Piscataquis 
Valley"  from  Howland  to  Milo,  and  then  silty  clay  extends  up  the  Piscataquis 
to  Dover  and  up  the  Pleasant  River  to  Brownville.  •  The  gravel  of  the 
plain  east  of  Milo  Village  is  so  much  coarser  than  the  drift  of  the  Pleasant 
River  Valley  north  of  the  plain  for  several  miles,  and  the  slopes  of  the 
valley  are  so  gentle,  that  it  is  quite  certain  this  plain  is  glacial  gravel.  The 
plain  shows  several  of  the  characteristics  of  the  delta.  The  Pleasant  River 
glacial  gravels  do  not  seem  to  have  connections  south,  a  fact  which  strongly 
supports  the  conclusion  that  they  were  terminated  by  delta-plains  at  the 
ice  front  during'  the  final  melting  and  recession  of  the  great  glacier. 

LILLY   BAY-WILLIMANTIC  OSAR. 

A  medium-sized  ridge  leaves  Moosehead  Lake  at  Lilly  Bay.  The 
gravel  is  here  not  much  rounded.  The  ridg-e  is  described  as  following  a 
rather  crooked  line  of  low  passes  southward,  and  then  down  the  valley  of 
Wilson  Stream,  expanding  into  broad  plains  in  Willimantic,  west  of  Sebec 
Lake.  No  glacial  gravel  extends  along  Sebec  Lake  and  Stream,  and  I 
can  not  trace  any  extension  of  this  system  south  into  Guilford  or  Dover. 
This  makes  it  highly  probable  that  the  broad  sedimentary  plain  of  Wilson 
Stream  above  Sebec  Lake  is  really  a  frontal  plain  composed  of  matter 
poured  out  by  glacial  streams  into  the  valley  in  front  of  the  ice,  at  a  time 
when  tlie  ice  had  retreated  to  this  place.  There  is  very  little  alluvium  of 
any  kind  along  Sebec  Stream,  the  outlet  of  Sebec  Lake,  imtil  we  come  east 
to  within  2  miles  of  Milo  Village,  when  the  valley  widens  and  is  covered 
with  silty  clay  continuous  with  that  of  the  Piscataquis  and  Pleasant  River 
valleys.  This  clay  is  just  such  a  deposit  as  would  be  formed  in  the  valley 
by  the  Gletsehermilch  of  glaciers  still  existing  20  miles  or  more  to  the 
north. 

We  now  pass  beyond  the  region  included  between  tlie  two  principal 
branches  of  the  long  Moosehead  Lake-Penobscot  Valley  system. 

ETNA-MONROE  SYSTEM. 

We  now  reach  a  part  of  the  State  where  those  parts  of  the  gravel  sys- 
tems which  contain  gaps  as  a  constant  and  conspicuous  feature  are  as  long 
as  or  longer  than  those  parts  where  the  ridg-e  is  continuous. 


136  GLACIAL  GRAVELS  OF  MAINE. 

A  series  of  ridges  separated  by  intervals  of  various  lengths  up  to  IJ 
miles  begins  in  the  south  part  of  Stetson  near  the  top  of  a  rather  low  east- 
and-west  hill.  The  series  passes  around  the  west  and  south  sides  of  Etna 
Pond  and  then  southeastward.  It  passes  a  few  rods  south  of  Carmel  station 
of  the  Maine  Central  Railroad,  and  within  2  miles  turns  rather  abruptly 
southward  along  the  main  tributary  of  the  Soudabscook  Eiver.  In  this 
part  of  its  course  it  is  nearly  continuous.  For  several  miles  in  the  northern 
part  of  Newburg  it  takes  the  form  of  an  osar-plain,  i.  e.,  a  level  plain  of 
well-rounded  gravel  filling  the  bottom  of  the  valley,  being  bordered  on  each 
side  by  a  sheet  of  sedimentary  clay  which  extends  back  to  the  hills.  The 
clay-and-gravel  deposits  have  substantially  the  same  upper  level  or  surface. 
The  osar  does  not  follow  the  axis  of  the  valley  exactly,  but  is  often  nearer 
to  one  side.  In  the  central  part  of  Newburg  the  gravels  leave  the  valley 
of  the  Soudabscook  and  go  south  up  and  over  a  hill  fully  150  feet  high. 
Above  this  point  the  valley  of  this  stream  contains  only  a  scanty  valley 
drift  reaching  scarcely  5  feet  above  the  stream,  a  great  contrast  to  the  broad 
and  deep  sheets  of  gravel  and  clay  which  fill  the  part  of  the  valley  where 
the  osar  river  flowed.  This  clay  bordering  the  central  gravel  plain  is  a 
good  example  of  what  I  have  named  the  osar  border  clay.  The  gravel 
itself  was  deposited  in  a  rather  broad  channel  in  the  ice.  This  channel  sub- 
sequently broadened  so  as  to  extend  across  the  whole  valley  and  the  clay 
was  deposited  at  the  flanks  of  the  older  gravel  plain.  A  lake  150  feet  deep 
would  naturally  gather  here  on  the  north  side  of  the  hill,  but  it  was 
inclosed  b}^  ice  walls  on  the  sides  (at  least  most  of  the  time  of  its  existence), 
otherwise  it  would  have  extended  up  the  valley  for  some  miles  and  the 
upper  part  of  the  valley  would  be  covered  by  lacustrine  sediments. 

On  the  hill  above  referred  to  the  gravel  is  much  interrupted.  At  the 
southern  base  of  the  hill  it  spreads  out  into  a  broad  deposit  nearly  one-half 
mile  across.  This  is  in  the  valley  of  another  branch  of  the  Soudabscook, 
which  flows  northeastward,  past  South  Newburg,  into  Stetsons  Pond  at 
West  Hampden.  The  gravels  take  an  unusual  form.  There  are  several 
gently  sloping  terraces,  rising  one  above  the  other,  each  separated  from  the 
adjoining  ones  by  rather  steep  bluffs  which  are  nearl}'  parallel  widi  the 
strike  of  the  hillside.  The  higher  terraces  on  the  north  are  narrower  and 
composed  of  coarser  material  than  those  on  the  south.     The  deposit  as  a 


ETNA-MONROE  SYSTEM.  137 

whole  has  some  of  the  characteristics  of  a  fan-shaped  delta.  A  jjlaiii  of 
marine  clays  extends  from  this  point  eastward  to  the  Penobscot  River. 
Between  this  gravel  plain  and  Sonth  Newbnrg,  2  miles  distant,  there  are 
several  small  low  ridges  or  plains  of  rather  fine  gravel,  which  fact  favors 
the  conclusion  that  during  the  final  melting  there  was  a  limited  overflow 
from  the  larger  plain  (then  a  glacial  lake)  eastward  into  the  arm  of  the  sea 
which  then  occupied  the  valley  where  now  is  South  Newl^urg.  South  of 
the  delta-plain  above  mentioned  lies  a  region  of  valleys  and  low  hills.  The 
glacial  gravels  cross  these  as  a  series  of  broad  ridg-es,  separated  by  gaps, 
which  soon  expand  into  a  pretty  large  plain,  about  2  miles  long  and  three- 
fourths  of  a  mile  wide.  Along  one  part  of  the  plain  is  a  ridge  rising  above 
the  rest  of  the  plain.  This  ridge  expands  in  places  into  reticulated  ridges 
inclosing  deep  kettleholes.  Bordering  this  ridge,  which  is  composed  chiefly 
of  large  pebbles,  cobbles,  and  bowlderets,  is  the  rather  level  plain  of  finer 
sand  and  gravel.  Evidently  the  central  ridge  was  deposited  in  a  channel 
between  ice  walls.  The  bordering  plain  is  a  delta,  deposited  either  between 
ice  walls  in  a  glacial  lake  or  in  the  sea.  This  plain  is  situated  east  and 
northeast  of  Monroe  Village,  and  the  Monroe  Fair-ground  is  situated  on  it. 
Marine  clays  widely  cover  the  valley  of  Marsh  Stream  to  a  point  far  west 
of  Monroe.  South  of  Monroe  Village  the  gravel  takes  the  form  of  lenticu- 
lar ridges  or  elongated  domes.  From  this  point  south  the  gaps  are  a  very 
regular  and  constant  part  of  the  system,  and  they  do  not  seem  to  depend 
on  the  surface  features  of  the  land  for  their  distribution;  at  least  if  there  be 
such  a  dependence  it  is  not  easily  detected.  The  system  extends  southward 
through  Monroe,  crosses  a  low  divide  in  Swanville,  skirts  the  western  side 
of  Goose  Pond,  and  then  takes  a  nearly  straight  course  to  Belfast  Bay,  near 
the  line  between  Belfast  and  Searsport.  South  of  Goose  Pond  the  system 
for  some  miles  takes  the  form  of  a  low  plain  one-eighth  to  one-fourth  of  a 
mile  broad.  The  material  becomes  finer  on  the  south,  and  is  a  delta-plain, 
laid  down  probably  in  a  bay  of  the  sea  inclosed  at  the  sides  by  glacial  ice. 

The  gaps  between  these  separated  gravel  deposits  are  not  due  to  ero- 
sion, unless  locally  here  and  there  at  the  crossing  of  streams,  but  the  gravel 
was  deposited  discontinuously  in  this  way.  Between  the  separate  deposits 
lie  undisturbed  till  or  marine  clay. 

The  length  of  the  system,  from  Stetson  to  Belfast  Bay,  is  about  35  miles. 


138  GLACIAL  GRAVELS  OF  MAINE. 

LOCAL  BSKERS  IN  JACKSON. 

A  ridge  of  subangular  glacial  gravel  extends  about  one-fourth  of  a  mile 
north  from  Jackson  Village.  About  2  miles  east  of  the  village  is  a  plain 
nearly  1  mile  long  and  one-fourth  mile  wide.  It  is  near  Fletchers  Mill,  on 
Marsh  Stream.  Another  similar  plain  is  found  near  Marsh  Stream  at  the 
mouth  of  Emery  Brook,  about  2  miles  west  of  Monroe  Village.  The  gravel 
of  these  small  plains  is  coarser  on  the  north  and  west;  they  are  probably 
deltas  deposited  in  the  arm  of  the  Penobscot  Bay  which  once  extended  for 
many  miles  up  both  branches  of  Marsh  Stream. 

The  till  in  Jackson  shows  a  great  variety  of  heaps  and  ridges,  probably 
owing  to  the  fact  that  Jackson  lies  just  south  of  the  high  hills  of  Troy  and 
Dixmont. 

WALDO-BELFAST  BAY   SYSTEM. 

This  is  a  short  series,  consisting  of  short  and  broad  ridges  or  plains, 
also  of  domes  or  mounds  of  glacial  gravel.  The  system  begins  in  the  north- 
eastern part  of  Waldo  and  extends  southward  along  the  valley  of  Westcott 
Stream  to  City  Point,  at  the  head  of  Belfast  Bay.  Toward  the  south  the 
deposits  continue  to  grow  smaller,  and  the  last  of  them  that  is  now  above 
the  sea  is  only  a  small  hummock,  not  more  than  75  or  100  feet  in  diameter 
at  the  base.     The  system  is  discontinuous  throughout  its  whole  course. 

It  is  5  miles  long. 

BROOKS-BELFAST  SYSTEM. 

This  is  a  discontinuous  series.  It  appears  to  begin  in  the  northeastern 
part  of  Bi-ooks,  perhaps  extending  into  Jackson.  It  crosses  the  valley  of 
the  south  branch  of  Marsh  Stream  about  1  mile  east  of  Brooks,  here  being 
joined  by  a  short  branch  from  the  northwest.  It  then  goes  up  and  over 
the  hills  by  the  same  pass  in  which  the  Maine  Central  Railroad  is  con- 
structed, and  its  course  lies  near  the  railroad  in  the  valley  of  Westcott 
Stream  to  Waldo  station.  The  railroad  liere  turns  eastward  and  follows 
the  lower  valley  of  Westcott  Stream,  while  the  gravel  takes  a  straight 
course  southward  past  Evans  Corner  to  near  the  Head  of  the  Tide,  Bel- 
fast. Near  Waldo  station  the  series  takes  the  form  of  broad  ridges  and 
rather  level-topped  plains  bordered  by  marine  clay.  These  are  apparently 
delta-plains,  but  since  they  do  not  spread  out  in  fan  shape,  as  they  could 
easily  have  done  if  the  glacial  river  ilowed  into  the  open  sea,  they  must 


SYSTEMS  OF  GLACIAL  GRAVELS.  139 

have  been  deposited  in  a  glacial  lake  or  in  a  broad  channel  inclosed  between 
ice  walls  and  opening  into  the  sea.  South  of  the  delta-plains  the  lenticular 
mounds  grow  smaller,  and  the  last  known  deposit  of  the  series  is  only  a 
small  hummock,  which  was  once  wholly  covered  by  marine  clay  and  laid 
bare  by  excavations. 

The  system  is  about  15  miles  long. 

LOCAL  ESKERS  IN  DEXTER. 

About  2  miles  east  of  Dexter  on  the  road  to  Gaidand  are  two  small 
ridges  or  hillside  eskers.  They  begin  on  the  south  side  of  a  long  sloping 
hill,  not  far  above  its  base,  and  extend  out  into  the  rather  level  valley  a 
short  distance.  They  enlarge  somewhat  at  their  south  ends,  but  not  into  a 
well-developed  delta,  such  as  ends  in  sand  and  finally  clay.  These  ridg-es 
are  less  than  one-fourth  of  a  mile  in  length. 

A  short  ridge  of  glacial  gravel  is  found  near  the  railroad  station  in 
Dexter  Village.  The  valley  of  Dexter  Stream  is  covered  by  very  abun- 
dant alluvium  of  uncertain  origin.  It.  is  more  abundant  than  usual  in 
a  valley  of  this  size.  It  is  possible  some  of  this  rather  fine  sediment  is 
an  osar-plain  connecting  with  the  system  next  to  be  described.  I  have 
not  explored  the  valley  north  of  Dexter  Village,  but  have  recently  heard  of 
bogs  without  visible  outlets  being-  found  not  far  north  of  Dexter.  If  this 
is  so,  there  probably  is  a  system  of  glacial  gravels  along  this  stream,  and 
the  fine  silt  and  clay  in  the  valley  below  Dexter  may  be  frontal  matter 
derived  from  this  stream  at  a  time  when  the  ice  had  retreated  to  some  point 
near  or  north  of  Dexter.  This  interpretation  would  well  accord  with 
the  finding  of  the  hillside  eskers  east  of  the  village. 

CORINNA-DIXMONT    SYSTEM. 

As  above  noted,  this  system  may  extend  to  Dexter  or  farther  north,  but 
I  was  not  able  to  determine  the  liinit  with  certainty.  A  well-defined  series 
of  glacial  gravels  is  found  in  the  valley  of  Alder  Stream  for  3  miles  north  of 
Corinna,  and  thence  southward  to  the  junction  of  this  stream  with  Dexter 
Stream.  The  gravel  takes  the  form  of  level  plains  in  several  places,  and 
tliere  are  a  number  of  gaps.  Its  course  crosses  Newport  Pond.  It  appears 
as  an  osar  ridge  on  the  south  side  of  this  pond,  and  takes  a  quite  straight 
general  course  southward  past  East  Newport  station,  on  the  Maine  Central 


140  GLACIAL  GEAVELS  OF  MAINE. 

Railroad,  to  Plymouth  Village.  The  road  from  East  Newport  to  Plymouth 
is  made  on  top  of  the  ridge  for  several  miles.  Just  north  of  Plymouth 
Village  the  road  crosses  a  hill  about  125  feet  high.  The  gravel  system 
here  bends  to  the  east  of  the  road  for  a  short  distance  and  crosses  the  hill 
at  an  elevation  about  50  feet  lower  than  the  road.  At  the  northern  base 
of  this  hill  there  is  a  plain  of  gravel  with  much  sand.  The  plain  is  near 
one-fourth  of  a  mile  wide,  and  indicates  a  checking  of  the  glacial  streams 
north  of  the  hill.  From  East  Newport  to  this  point  the  osar  traverses 
a  jolain  that  is  covered  by  sedimentary  clay^border  clay.  We  have  seen 
that  the  osar  river  turned  east  in  order  \o  cross  the  hill  north  of  Plymouth 
at  a  low  part  of  the  hill,  but  by  bending  about  the  same  distance  west 
the  stream  could  have  flowed  around  the  hill  along  a  valley  of  natural 
drainage.  The  gravel  is  scanty  on  top  of  the  hill,  but  becomes  abundant 
near  its  soiithern  base  in  the  outskirts  of  Plymouth  Village.  The  ridge 
next  crosses  Plymouth  Pond,  jjlainly  showing  as  a  natural  roadway  extend- 
ing across  the  valley,  but  it  is  submerged  for  a  short  distance.  The  road 
is  made  on  top  of  this  natural  embankment  while  crossing  the  pond  and 
bordering  swamp.  The  system  now  begins  to  ascend  a  hill  100  feet  high, 
and  at  once  expands  into  a  plexus  of  broad,  rather  parallel  ridges  inclosing 
several  kettleholes.  Approaching  the  top  of  the  hill,  the  several  ridges 
coalesce  into  a  flat-topped  plain  near  one-eighth  mile  wide.  It  is  com- 
posed chiefly  of  sand,  and  is  a  fair  type  of  the  broad  osar.  No  gravel  is 
found  on  the  top  of  the  hill  for  a  short  distance;  then  it  begins  again  and 
continues  down  the  hill  to  North  Dixmont.  It  here  takes  the  form  of  a 
narrow  ridge  50  to  75  feet  high,  having  steep  lateral  slopes.  In  several 
exposures  the  strata,  as  shown  in  cross  section  of  the  ridge,  dip  mono- 
clinally  eastward,  as  if  the  channel  in  the  ice  enlarged  on  the  east  side 
toward  the  open  valley.  The  ground  rises  to  the  west,  and  this  makes  it 
a  possible  hypothesis  that  the  ice  flowed  eastward  enough  to  compensate 
for  the  natural  enlargement  of  the  channel  westward. 

Going  southward,  we  find  the  ridge  growing  broader  and  lower,  and  it 
finally  spreads  out  into  a  rather  level  plain  one-eighth  of  a  mile  wide.  This 
becomes  finer  in  composition  toward  the  south,  and  finally  becomes  sand. 
It  is  bordered  at  the  sides  and  south  end  by  a  rather  steep  bluff,  which 
overlooks  the  valley  of  Martin  Stream.  This  is  a  small  stream  which  rises 
in  Troy,  then  flows  northeastward  through  Dixmont,  when  it  turns  north- 


COEIiSrNA-DIXMONT  SYSTEM.  '        141 

west  past  Plymouth  Village  and  empties  into  the  Sebasticook  River  a  few 
miles  below  Newport  Village.  In  Dixmont  the  valley  of  this  stream  is 
very  level  and  a  half  mile  or  more  broad.  A  continuous  plain  of  clay  and 
silty  clay  overlying  fine  sand  (the  reverse  order  of  the  ordinary  valley 
alluvium)  is  found  in  this  valley  all  the  way  from  Troy,  through  Dixmont 
and  Plymouth  and  thence  along  the  Sebasticook  and  Kennebec  valleys,  to 
the  sea.  This  clay  is  proved  by  its  fossils  to  be  marine  as  far  east  as  Pitts- 
field,  and  perhaps  as  far  as  Newport.  I  have  often  suspected  that  a  narrow 
arm  of  the  sea  connected  the  Kennebec  and  Penobscot  bays  of  that  time, 
along  the  low  ground  where  Etna  Bog  is.  Now  the  gravel-and-sand  plain 
which  seems  to  termiiiate  the  Corinna-Dixmout  system  has  the  general 
character  of  a  delta  deposited  where  rapid  streams  flowed  into  a  body  of 
still  water  and  are  rapidly  checked.  At  once  our  attention  is  called  to  the 
large  plain  of  fine  sediment  in  the  valley  of  Martin  Stream,  in  which  this 
delta  lies.  This  stream  is  only  a  small  brook,  and  ordinarily  streams  of 
that  size  would  deposit  only  a  very  little  alluvium.  Evidently,  at  the  time 
this  delta-plain  2  miles  southwest  of  North  Dixmont  was  being  formed  the 
valley  of  Martin  Stream  in  Dixmont  and  Troy  was  in  large  part  bare  of 
ice,  and  was  either  occupied  by  a  lake  contained  between  the  ice  on  the 
north  and  the  hills  over  which  the  ice  had  melted  at  the  south,  or  was  filled 
by  an  arm  of  the  sea.  But  the  Kennebec  Bay  of  that  period  could  reach 
this  place  only  along  the  valley  of  Martin  Stream  through  Plymouth,  and 
if  the  sea  extended  from  that  direction  the  delta  would  have  been  formed 
in  the  valley  of  Martin  Stream  at  Plymouth  Village  instead  of  several 
miles  south  of  that  place.  It  is  evident  that  when  the  delta  southwest  of 
North  Dixmont  was  being  deposited,  the  ice  must  still  have  remained  at 
Plymouth  Village,  and  this  would  prevent  any  communication  with  the  sea 
in  the  Kennebec  Valley.  Was  there  an  arm  of  the  sea  in  the  valley  of 
Martin  Stream  which  connected  with  the  Penobscot  Bay?  I  have  traced 
the  marine  clay  from  the  Penobscot  River  as  far  west  as  Etna  Pond,  but 
between  that  point  and  Plymouth  is  an  area  not  explored.  According  to 
Col.  A.  W.  Wilder,  quoted  in  Wells's  Water  Power  of  Maine, ^  the  elevation 
of  Plymouth  Bog  is  256  feet,  and  that  of  Plymouth  Village  275  feet.  As 
elsewhere  suggested,  the  sea  may  have  stood  at  a  higher  elevation  in  the 
interior  than  on  the  coast,  but  in  the  absence  of  direct  proof  to  that  effect, 

'The  Water  Power  of  Maine,  by  Walter  Wells,  p.  89,  Augusta,  1869. 


142  GLACIAL  GRAVELS  OF  MAINE. 

the  clays  of  the  valley  of  Martin  Stream  iu  Plymouth  and  Dixmont  must 
be  considered  as  probably  having  been  deposited  above  the  highest  level  of 
the  sea,  and  therefore  in  a  lake  contained  between  the  ice  which  was  still 
unmelted  toward  the  north  and  the  high  east-and-west  hills  of  Troy  and 
Dixmont  on  the  south.  If  so,  where  did  the  supposed  lake  overflow"? 
There  are  two  low  passes  b}^  which  the  water  of  such  a  lake  could  have 
escaped  southwestward  into  the  Sand}-  Stream  Valle}"  in  Thorndike,  after 
the  waters  had  accumulated  to  a  depth  of  about  100  feet,  provided  no 
barrier  of  ice  then  existed  in  that  direction.  But  no  clays  analogous  in  any 
way  to  those  of  the  Martin  Stream  iu  Dixmont  are  foimd  along  these  val- 
leys, and  hence  there  is  no  proof  of  an  overflow  this  way;  neither  do  I 
find  proof  of  such  overflow  westward  into  Troy.  The  order  of  events 
here  is  probably  about  as  follows:  The  Corinna-Dixmont  glacial  river 
emptied  for  a  time  into  an  enlarging  glacial  lake,  inclosed  between  the  ice 
and  the  high  hills  on  the  east  and  south.  The  outlet  of  this  lake  was 
toward  the  Penobscot  Bay  or  in  some  imknown  direction.  During  the 
retreat  of  the  ice  the  glacial  water  may  have  escaped  into  the  open  valley 
of  Martin  Stream  at  or  near  Plymouth  Village,  but  if  so  it  could  have  been 
for  only  a  short  time.  The  gravel  plain  at  the  north  base  of  the  hill 
situated  just  north  of  Plymouth  Village  may  point  to  another  glacial  lake, 
formed  north  of  that  hill,  and  the  clay  bordering  the  osar  northward  to 
East  Newport  may  have  been  deposited  by  a  broad  channel  which  practi- 
cally formed  an  enlargement  of  this.  lake.  There  are  plains  of  sedimentary 
clay  in  Plymouth  extending  an  unknown  distance  northeastward  toward 
Etna  Bog,  and  these  may  mark  an  overflow  to  the  Penobscot  Bay.  How 
far  this  is  marine  remains  to  be  determined  by  future  investigation. 
The  length  is  about  20  miles.-^ 

EAST   TBOY   KAMES. 

About  3  miles  southwest  from  the  delta-plain  in  which  the  Corinna- 
Dixmont  system  ends,  a  discontinuous  series  of  short  ridges  and  cones  of 
glacial  gravel  begins  on  the  hills  north  of  Martin  Stream,  crosses  the  valley 
of  that  stream  near  East  Troy,  and  then  ascends  the  hills  lying  to  the  south 
to  a  height  of  about  100  feet.  It  appears  to  end  in  a  thin  gravel  plain  a 
little  north  of  a  low  pass  leading  into  Jackson.     Not  far  north  of  where  the 

I  The  clays  extendiug  from  Dixmout  eastward  are  now  (1893)  considered  by  me  to  he  marine. 


TEOY-BELFAST  SYSTEM.  143 

gravel  disappears  is  a  cone  of  gravel  and  cobbles  80  feet  high.  The  Brooks- 
Belfast  and  Troy-Belfast  systems  are  both  so  situated  that  this  short  glacial 
river  might  connect  with  either  of  them,  but  I  have  not  been  able  to  trace 
any  connection  with  them.  The  clay  in  the  valley  of  Martin  Stream 
overlies  these  gravels;  hence  the  flow  of  this  glacial  stream  dates  pre^dous 
to  the  time  when  the  terminal  delta  of  the  Coriuna-Dixmont  system  was 
deposited  in  a  body  of  water  then  filling  this  valley. 

This  short  series  does  not  have  a  wholly  satisfactory  beginning  or  end, 
but  I  have  not  been  able  to  trace  any  connections  with  other  gravels.  It 
may  at  one  time  have  been  2:)art  of  the  Corinna-Dixmont  system. 

The  length  is  about  3  miles. 

TROY-BELFAST  SYSTEM. 

This  system  appears  to  begin  about  one- half  mile  soiith  of  the  road 
from  West  Troy  to  Troy  Post-Office  (Troy  Corner),  as  a  low,  north-aud- 
south  ridge,  which  shows  numerous  meanderings.  It  lies  in  a  region  of 
rather  low  hills,  forming  a  rolling  plain  lying  north  of  the  much  higher  hills 
of  southern  Troy  and  of  Thorndike.  At  the  northern  base  of  these  high 
hills  this  ridge  is  joined  in  the  southern  part  of  Troy  by  a  rather  level 
gravel  plain  from  the  west.  It  is  nearly  one-fourth  mile  in  length  and  per- 
haps half  as  wide.  This  appears  to  be  a  delta,  either  of  a  lake  wholly 
glacial  or  of  a  lake  confined  between  the  ice  on  the  north  and  the  hills  on 
the  south.  The  gravel  system  then  crosses  a  low  divide  in  a  narrow  pass 
and  follows  the  valley  of  Parsons  or  Halls  Brook  for  2  miles  southwestward. 
It  then  abandons  this  valley  and  follows  a  low  pass  into  the  valley  of 
Higgins's  Stream.  It  follows  this  valley  southward  for  several  miles,  passing 
about  one-half  mile  Avest  of  the  Friends'  Meeting  House  in  Thorndike.  It 
leaves  this  valley  not  far  from  Thorndike  Corner,  and  by  a  crooked  route 
penetrates  the  hilly  region  of  eastern  Knox  and  the  northwestern  part  of 
Brooks,  crossing  several  pretty  high  hills.  It  then  follows  the  valley 
of  Marsh  Stream,  parallel  with  the  railroad,  to  a  point  about  1  mile  west  of 
Brooks  Village,  when  it  turns  southward  along  a  low  valley.  It  soon  goes 
up  and  over  a  hill  100  or  more  feet  high  and  descends  to  Passagassawawkeag 
Pond.  From  this  point  south  its  course  lies  in  a  rather  level  region  in 
Brooks  and  Waldo.  In  Waldo  it  expands  into  a  rather  level  plain  several 
miles  long  and  one-eighth  of  a  mile  or  more  in  breadth.     The  material 


144  GLACIAL  GEAVELS  OF  MAINE. 

becomes  finer  toward  the  south,  and  gradually  passes  into  the  marine  clay 
at  an  elevation  of  200  feet  or  a  little  more.  The  plain  is  probably  a  delta 
deposited  in  a  bay  of  the  sea  between  ice  walls.  South  of  this  plain  are  a 
few  small  gravel  deposits,  forming  a  discontinuous  series,  with  long  gaps. 
The  system  seems  to  end  in  the  northern  part  of  Belfast.  The  way  in 
which  most  of  the  longer  gravel  systems  reach  their  maximum  develop- 
ment at  about  the  contour  of  230  feet  and  then  become  less  and  less  till 
they  end  at  or  not  far  above  the  sea,  is  well  expressed  by  the  Western 
phrase,  "peter  out." 

This  glacial  river  brought  down  a  large  amount  of  sediment  for  so 
short  a  stream.  Its  course  is  circuitous,  and  for  most  of  the  distance  is  in 
a  very  hilly  country.  Five  times  it  left  drainage  valleys  and  crossed  hills 
into  other  valleys,  none  of  the  hills  being  more  than  200  nor  less  than  100 
feet  high.  Its  larger  deflections  occurred  invariably  in  order  that  it  might 
cross  the  hills  by  the  lower  passes.  The  system  is  an  instructive  example 
of  the  power  of  the  higher  hills  to  deflect  the  glacial  rivers.  Wlien  it 
crosses  hills,  the  gravel  is  usually  abundant  near  the  southern  base  of  the 
hills  or  in  the  level  plains,  while  it  is  scanty  near  the  tops  of  the  cols. 

It  is  about  20  miles  in  length. 

MORRILL-BELFAST  BAY  SYSTEM. 

This  is  a  discontinuous  system  of  short  ridges,  small  plains,  and  len- 
ticular mounds  or  domes  of  glacial  gravel  separated  by  intervals  varyhig 
in  length  from  one-eighth  to  one-half  of  a  mile. 

The  series  begins  in  the  northern  part  of  Morrill  and  takes  a  southeast 
course  over  a  level  plain  past  Morrill  Village  to  Poors  Mill,  in  the  north- 
western part  of  Belfast.  It  then  goes  up  and  over  a  hill  about  100  feet 
high  and  descends  the  valley  of  Little  River,  ending  in  a  beach  cliff  of 
glacial  gravel  on  the  shore  of  Belfast  Bay,  a  few  rods  south  of  the  mouth 
of  Little  River. 

Near  Poors  Mill  the  system  expands  into  a  somewhat  level  plain,  sug- 
gesting a  small  marine  delta.  The  whole  region  traversed  by  the  system 
has  been  under  the  sea,  and  the  gravels  are  more  or  less  covered  by  the 
marine  clay. 

An  interesting  formation  is  found  in  the  valley  of  Little  River  at  the 
road  from  Belfast  to  Belmont.     The  axis  of  one  of  the  ridges  of  this  sys- 


MOEEILL-BBLFAST  BAY  SYSTEM.  145 

tern  is  shown  by  the  deep  cut  at  the  road  to  consist  of  till.  A  central  ridge 
of  till  was  covered  on  both  slopes  by  10  or  more  feet  of  glacial  sand  and 
gravel,  some  of  it  reaching  the  top  of  the  ridge,  and  subsequently  the  whole 
was  buried  beneath  several  feet  of  marine  clay.  This  suggests  the  ques- 
tion whether  a  core  of  till  may  not  often  occupy  the  central  and  basal  por- 
tions of  the  low  rounded  ridges  of  the  discontinuous  systems  of  glacial 
gravel.  I  have  examined  a  large  number  of  the  lenticular  masses  char- 
acteristic of  this  type  of  gravels,  and  this  is  the  only  case  where  they  could 
be  proved  to  contain  unmodified  till.  Yet  these  excavations  seldom  went 
to  the  bottom  of  the  deposit,  and  their  number  is  small  as  compared  with 
the  whole  number  of  similar  bodies.  It  is  possible  a  till  nucleus  may  be 
somewhat  common  in  these  mammillary  kames. 
The  length  of  the  system  is  about  1 1  miles. 

GENERAL    NOTE    ON    THE    BELFAST    REGION. 

It  will  be  seen  that  five  gravel  systems  converge  to  Belfast  Bay.  The 
glacial  scratches  last  made  converge  to  the  same  place,  while  the  earlier 
scratches  were  more  nearly  parallel.  The  discontinuous  systems  of  gravel 
are,  therefore,  nearly  parallel  with  the  scratches  last  made,  and  they  apj)ear 
to  date  from  the  last  part  of  the  Glacial  period.  Most,  perhaps  all,  of  the 
discontinuous  systems  expand  at  some  ^Joint  into  delta-plains,  the  largest  of 
which  are  situated  at  or  not  far  below  the  contour  of  230  feet.  Toward  the 
south  the  gravel  deposits  become  smaller  and  the  intervals  between  them 
longer. 

The  large  island  of  Isleboro  lies  in  the  midst  of  Penobscot  Bay,  to 
the  south  and  east  of  Belfast,  and  in  the  line  of  these  systems  prolonged. 
The  island  shows  a  limited  amount  of  beach  gravel,  but  no  glacial  gravel 
that  I  could  find.  Three  of  the  Belfast  Bay  gravel  systems  come  down  to 
the  shore,  but  their  diminishing  size  toward  the  sea  indicates  that  there  was 
probably  no  large  development  of  glacial  gravel  over  what  is  now  the  sea. 

LOCAL   BSKERvS   IN    TEOT   AND    PLYMOUTH. 

A  broad,  level  region  covered  by  marine  clay  extends  from  Unity 
Pond  northeastward  through  Troy.  It  is  continuous  with  a  line  of  sedi- 
mentary clay  extending  northward  through  Plymouth  and  Detroit  to  the 

MON  XXXIV 10 


146  GLACIAL  GEAVELS  OF  MAINE. 

Sebasticook  River.  Part,  j^erliaps  all,  of  these  clays  are  marine,  but  the 
estuarine,  fluviatile,  and  lacustrine  drift  are  all  present  in  that  region  and 
difficult  to  distinguish.  On  the  slopes  of  rather  low  hills  that  border  this 
clay-covered  plain  on  the  south  and  east  are  several  local  kames.  One  of 
these  is  situated  in  the  southwestern  part  of  Plymouth,  at  the  southern  end 
of  a  hill  bordered  on  each  side  by  a  low  north-and-south  valley.  It  ends 
near  the  upper  limit  of  the  sedimentary  clays.  Two  other  deposits  of 
glacial  gravel  are  found  in  the  north-and-south  valley  of  a  small  brook 
flowing  north  into  Carlton  Stream.  They  are  situated  a  short  distance 
north  of  Troy  Center.  Still  another  is  found  on  the  east  side  of  a  north- 
and-south  valley  near  Cooks  Corner,  about  three-fourths  of  a  mile  west 
of  Troy  Center.  It  is  a  short  terrace,  only  a  few  rods  long,  about  40  feet 
above  the  bottom  of  the  valley  and  about  midwa}-  up  the  slope.  It  has 
been  cut  through  by  the  road  to  a  depth  of  several  feet.  On  the  south 
side  of  the  road  the  terrace  is  plainly  stratified,  the  strata  dipping  down  the 
hill  and  transversely  to  the  ridge.  The  diiferent  layers  vary  much  in  com- 
position, some  being  fine  sand,  others  coarse  gravel  and  cobbles,  slightly 
polished  and  rounded.  Near  the  surface  the  mass  is  pellmell  in  structure. 
On  the  north  side  of  the  road,  and  only  about  25  feet  away,  the  whole 
section  exposed  shows  the  pellmell  structure.  The  separate  pebbles  and 
cobbles  are  like  those  at  the  south  side  of  the  road  in  form,  and  the  two 
sections  difter  in  structure  only.  Both  have  plainly  been  water-assorted 
and  the  finer  parts  of  the  till  have  been  washed  away.  It  will  be  noted 
that  the  pellmell  layer  at  the  south  overlies  the  stratified  portion.  Ajjpa- 
rently  a  small  kame  was  first  deposited  with  a  stratified  structure,  and 
subsequently  the  advance  of  the  ice  pushed  the  sediments  forward  suffi- 
ciently to  mix  up  the  several  layers  near  the  surface  and  destroy  the 
stratification. 

The  hills  extending  from  Palermo  to  Dixmout  and  Newburg  rise  300 
to  600  feet  above  the  broad  plain-like  valleys  of  the  Sebasticook  and 
Soudabscook,  situated  to  the  north  of  them.  These  hills  would  stop  the 
flow  of  ice  soiithAvard  during  the  final  melti:^g  of  the  great  glacier  long- 
before  the  ice  had  disappeared  in  the  lowlands  to  the  north.  As  the  ice 
gradually  retreated  northward,  it  would  often  happen  that  lakes  ^'S'ould  be 
inclosed  between  the  ice  and  the  hills  to  the  south  of  them.  Within  the 
limited  time  these  lakes  were  in  existence  no  very  large  amount  of  sedi- 


I     \, 


GEORGES  RIVER  SYSTEM.  147 

meiit  could  have  beeu  deposited,  except  where  the  larger  glacial  rivers 
flowed  into  them.  It  is  possible  that  some  of  these  lakes  left  too  scanty 
sediment  to  be  now  recognizable.  The  glacial  lakes  of  central  Dixmont, 
as  well  as  others  to  be  hereafter  named,  also  the  short  kames  of  Plymouth 
and  Troy,  seem  to  be  connected  phenomena,  all  pointing  to  the  time  when 
the  ice  front  had  retreated  a  short  distance  north  of  the  hills.  There  was 
probably  but  little  motion  of  the  ice  at  this  time. 

1.  A  still  higher  range  of  east-and-west  hills  lies  only  about  30  miles 
to  the  north  of  the  Palermo-Dixmont  Hills — those  lying  south  of  the  Pis- 
cataquis River.  These  would  cut  off  the  southward  flow  of  the  ice  nearly 
as  soon  as  the  lower  hills  to  the  south.  Thenceforth  there  would  be  no 
pressure  and  supply  of  ice  adequate  to  cause  much  advance  of  the  ice  even 
over  so  level  a  plain  as  the  Sebasticook  Valley. 

2.  I  have  been  able  to  find  no  very  noticeable  terminal  moraines  on  the 
northern  slopes  of  the  Palermo-Dixmont  Hills  at  the  places  where  I  have 
crossed  them,  though  there  are  many  irregular  heaps  of  till,  and  these  may 
yet  be  explained  as  the  best  approach  to  a  terminal  moraine  which  can  be 
made  by  a  mass  of  rather  slow  ice  that  is  not  receiving  its  moraine  stuff  on 
its  surface,  but  from  below,  and  is  gradually  retreating. 

3.  But  that  there  was  some  motion  is  probably  proved  by  the  observa- 
tions at  Cooks  Corner,  Troy,  where  we  seem  to  have  an  instance  of  the  ice 
advancing  and  obliterating  the  stratification  of  the  surface  portion  of  a 
kame.^ 

GEORGES  RIVER  SYSTEM. 

This  is  a  discontinuous  system  of  short  ridges  and  lenticular  hummocks. 
It  begins  about  3  miles  south  of  North  Searsmont.  The  gravel  here  is 
plainl)'"  Avater  assorted,  but  the  stones  are  only  a  little  polished,  retaining 
their  till  shapes  except  at  the  angles.  This  indicates  that  we  are  near  the 
north  end  of  the  system.  About  IJ  miles  south  of  this  is  another  short 
ridge;  the  next  one  is  in  the  southwest  part  of  Searsmont  Village,  and  from 
this  point  the  series  lies  near  Georges  River  all  the  wa,y  to  Thomaston. 
The  gravels  take  the  form  of  ridges  one-third  of  a  mile  or  less  in  length, 
and  they  are  more  often  mere  elongated  domes  or  mounds.  The  intervals 
are  several  times  as  long  as  the  ridges,  and  are  a  constant  feature  of  the 

'  For  the  facts  near  South  Albion,  see  pages  165  to  167. 


148  GLACIAL  GEAVELS  OF  MAINE. 

system  from  end  to  end.  They  vary  from  one-fourth  mile  to  IJ  miles  in 
length.  The  system  seems  to  end  in  a  cone  or  dome  of  glacial  gravel  sit- 
uated on  the  east  side  of  Georges  River,  just  above  the  railroad  bridge  at 
Thomaston.  The  gravel  lies  for  most  of  the  way  on  the  west  side  of  the 
river,  and  not  far  above  it.  The  system  lies  in  the  towns  of  Searsmont, 
Appleton,  Union,  Warren,  and  Thomaston. 

Near  Union  Village  a  small  mound  of  this  series  shows  contorted  and 
folded  strata  overlying  stratified  material.  The  dome  lies  so  low  in  the 
narrow  valley  that  it  is  very  improbable  an  ice  floe  came  from  the  north 
with  sufficient  force  to  distort  the  stratification.  ]\Iore  probably  the  gravel 
was  deposited  beneath  the  glacier  and  the  distortion  was  due  to  the  pressure 
of  the  moving  ice.  This  system  is  in  a  region  once  wholly  covered  by  the 
sea,  unless  on  the  extreme  north. 

The  length  is  about  8  miles. 

HARTLAND-MONTVILLE  SYSTEM. 

A  series  of  rather  short  ridges  begins  near  the  top  of  a  high  range  of 
hills  in  the  northern  part  of  St.  Albans.  It  extends  southward  past  Indian 
Pond  and  through  St.  Albans  Village,  and  thence  southwestward  along  a 
branch  of  the  Sebasticook  River.  A  short  distance  south  of  Hartland  Vil- 
lage this  series  unites  with  another,  which  takes  the  form  of  a  large  ridge 
beginning  at  the  south  shore  of  Moose  Pond  and  thence  taking  a  south- 
ern course  through  Hartland  Village.  The  gravel  of  the  latter  series  is 
much  rounder  than  that  of  the  St.  Albans  series,  which  is  but  little  worn. 
This  indicates  that  the  Moose  Pond  system  probably  has  a  northward  exten- 
sion. The  Cambridge-Harmony  eskers  hereafter  to  be  described  would 
naturally  be  a  part  of  this  system,  but  thus  far  I  can  not  prove  a  connec- 
tion. From  Hartland  the  united  series  continues  south  as  a  quite  continu- 
ous osar  ridge  for  several  miles.  In  the  southern  part  of  Pittsfield  the 
system  is  interrupted  at  several  places.  About  one-half  mile  north  of  Pitts- 
field  it  rises  into  a  rather  high  cone  called  the  "Pinnacle."  From  this  point 
southward  through  Pittsfield,  Burnham,  and  Unity  the  gravel  takes  the  form 
of  a  nearly  continuous  osar  with  very  gentle  lateral  slopes.  It  rises  10  to 
30  feet  above  the  marine  clay  which  borders  and  partly  covers  it.  In 
places  the  ridge  is  nearly  one-eighth  of  a  mile  broad,  yet  it  is  roimded  on 


HAETLAND-MONTVILLE  SYSTEM. 


149 


the  top,  so  that  its  cross  section  is  ahnost  always  arched.  At  Peltoma  Point 
the  ridge  crosses  the  Sebasticook  River.  The  river  can  be  forded  on  the  top 
of -the  ridge,  but  the  water  is  much  deeper  on  each  side.  It  also  rises 
nearly  to  the  surface  while  crossing  Unity  Pond.  The  ridge  broadens 
south  of  Unity  Pond,  and  from  near  Unity  Village  a  plain  of  complicated 
structure  extends  south  along  the  valley  of  Sandy  Stream  almost  to  Thorn- 
dike  station.  The  plain  fills  the  valley  from  side  to  side,  and  is  from  one- 
fourth  to  one-half  of  a  mile  wide.  It  shows  some  arched  ridges  of  gravel, 
bordered  and  often  covered  by  a  more  nearly  horizontally  stratified  stra- 


I'lu.  le.— Usar;  Pittstjfld. 


tum  of  fine  gravel,  sand,  and  clay.  Originally  there  were  kettleholes,  but 
most  of  them  have  been  filled  or  nearly  filled  by  the  later  sediments.  The 
sea  certainly  extended  to  Unity,  as  is  proved  by  marine  fossils.  How  far 
it  extended  up  the  valley  of  Sandy  Stream  is  uncertain.  The  contour  of 
230  feet  would  be  found  1  or  2  miles  south  of  Unity  Village.  The  origin 
of  this  plain  will  be  discussed  more  fully  later. 

Not  far  from  the  junction  of  Sandy  Stream  with  Half  Moon  Stream 
the  g'ravel  comes  up  out  of  the  valley.  For  a  half  mile  southward  it  takes 
the  form  of  a  broad  osar,  or  perhaps  delta-plain.     Then  for  several  miles  it 


150  GLACIAL  GEAVELS  OF  MAINE. 

is  a  two-sided  ridge,  or  often  a  terrace  on  the  hillside  west  of  Half  Moon 
Stream  and  50  feet  or  more  above  the  stream.  It  skirts  the  eastern  slopes 
of  a  high  hill  in  Unity  and  Knox,  and  near  Chandlers  Comer  crosses  the 
north  branch  of  Half  Moon  Stream,  and  within  one-eighth  of  a  mile 
disappears  as  a  two-sided  ridge.  Here  it  required  careful  observation  to 
determine  the  course  of  the  glacial  river,  and  the  result  was  quite  unex- 
pected. The  ridge  seems  to  be  lost  at  the  northern  base  of  a  range  of  hills 
300  to  500  feet  high.  This  range  is  several  miles  in  length  and  has  a 
northeast-and-southwest  direction.  Along  its  northern  base  is  a  depression, 
or  valley,  occupied  by  the  south  branch  of  Half  Moon  Stream,  which  flows 
northeastward.  It  is.  from  100  to  400  feet  wide  and  from  20  to  40  feet 
deep.  In  places  nothing  but  till  can  be  seen  in' the  steep  banks  inclos- 
ing it,  and  it  looks  like  a  large  canal  cut  in  a  deep  sheet  of  till.  In  other 
places  there  is  a  steep  wall  or  cliff  of  solid  rock  10  to  30  feet  high,  gla- 
ciated on  the  top,  bordering  the  valley  on  the  north,  and  it  is  thus  proved 
to  be,  in  jDart  at  least,  a  valley  of  preglacial  weathering  and  erosion.  It  is 
parallel  with  the  strike  of  the  upturned  pyritiferous  and  other  easily  weath- 
ered slates  and  schists  characteristic  of  this  region.  The  depression,  being 
transverse  to  the  direction  of  general  glacial  movement,  became  more  or 
less  filled  witli  till.  The  bottom  of  this  valley  is  covered  by  a  level-topped 
plain  of  sand  and  well-rounded  gravel  10  to  20  or  more  feet  in  thickness 
and  1  to  400  feet  wide.  The  south  branch  of  the  Half  ^loon  Stream  flows 
in  this  valley  for  about  2  miles,  but  it  is  a  small  brook,  such  as  ordinarily 
has  in  that  region  a  flood  plain  containing  only  1  to  3  feet  of  gravel,  the 
stones  of  which  have  the  till  shapes  almost  unchanged.  Plainly  it  is  incom- 
petent to  deposit  any  such  plain  of  sand  and  rounded  gravel  as  that  found 
in  its  valley.  At  one  place  the  brook  soaks  into  the  gravel  and  disappears 
except  in  time  of  flood,  when  it  can  not  seep  into  the  gravel  as  fast  as  the 
flow  from  above,  and  the  surplus  water  then  for  a  time  escapes  by  an  over- 
flow channel  over  a  rough  and  crooked  bed  evidently  recently  eroded  in 
the  till  and  gravel.  As  this  channel  is  dry  most  of  the  time,  it  is  locally 
known  as  the  "Dry  Stream."  The  water  which  disappears  in  the  gravel, 
as  above  described,  comes  out  again  about  one-fourth  of  a  mile  below  in 
the  form  of  boiling  springs,  which  are  eroding  the  gravel  more  rapidly, 
woi'king  from  beneath,  than  both  the  main  stream  and  the  overflow  stream 
combined  are  eroding  it  above  where  the  water  disappears  in  the  gravel. 
In  this  way  the  gravel  plain  has  been  eroded  for  more  than  one-fourth  of  a 


HARTLAND-MONTVILLE  SYSTEM.  151 

mile  from  where  we  lost  the  osar  as  a  two-sided  ridge.     It  is  evident  that 
the  valley  is  filled  by  a  rather  narrow  osar-plain.     It  extends  continuously 


Fig.  17.— Map  of  Hogback  Monntamj  MontvUle  and  -vicmity. 

for  about  1  mile  and  then  is  interrupted  by  two  or  three  gaps  of  one-third 
mile  each  or  thereabout.     In  places  the  erosion  has  revealed  arched  ridges 


152 


GLACIAL  GEAVELS  OF  MAINE. 


of  coarser  gravel,  wliicli  were  afterwards  covered  by  at  least  15  feet  of  fine 
gravel,  and  finally  sand  and  clay,  more  nearly  horizontally  stratified  and 
extending  across  the  valley  before  mentioned.  This  remarkable  depression 
is  bordered  much  of  the  way  by  a  steep  bank  of  till,  especially  on  the 
north.  It  extends  for  about  3  miles  along  the  base  of  the  high  hills,  when 
it  comes  out  to  a  very  low  uorth-and-south  pass  through  the  range.  To  the 
west  of  this  pass  rises  Hogback  Mountain,  and  I  will  term  it  the  Hogback 
Mountain  Pass.  For  a  short  distance  east  of  this  pass  the  bottom  of  the 
U-shaped  valle}^  containing  the  osar-plain  is  rather  stony,  then  for  one- 
fourth  mile  or  more  there  is  a  curious  narrow  bog,  occupying  the  northern 
part  of  the  valley,  while  on  the  south  side  is  a  level  terrace,  apparently 
composed  of  till.  This  terrace  is  several  feet  higher  than  the  bog.  A 
cross  section  of  the  valley  at  this  point  is  shown  in  fig.  18. 

This  part  of  the  valley  is  bordered  by  a  bluff  of  till  20  to  25  feet  high. 
It  is  as  steep  as  the  banks  of  most  streams,  and  shows  every  mark  of  an 

erosion  cliff".  In  this  part 
of  the  valley  only  very 
local  drainage  takes  place, 
since  even  the  little  south 
branch  of  the  Half  Moon 
Stream  enters  the  valley 
These  facts  establish  the  following  conclusions: 
The  osar  river  came  to  the  northern  base  of  the  high  hills  and  turned 
southwest  along  a  small  previously  existing  valley.  This  valley  consisted 
of  a  valley  in  the  rock  which  had  become  deeply  filled  by  till.  The  stream 
flowing  in  the  valley  eroded  the  till  to  a  considerable  depth,  leaving  its 
channel  bordered  by  cliffs  of  erosion.  The  narrow  bog  above  described 
was  once  an  erosion  channel  deeper  than  the  rest  of  the  glacial  channel. 
Originally  it  formed  a  small  lake,  but  by  degrees  has  become  peated 
over.  As  the  velocity  of  the  osar  river  diminished  during  the  final  melting, 
the  osar-plain  was  deposited  in  the  lower  part  of  the  channels,  though 
near  the  highest  point  of  the  region  crossed  but  little  if  any  gravel  Avas 
deposited. 

At  the  north  end  of  Hogback  Mountain  Pass  the  system  we  have  been 
tracing  from  Hartland  and  St.  Albans  is  joined  by  a  tributary  branch,  which 
begins  near  Freedom  Village.  It  follows  a  low  pass  southward,  over  a  hill 
about  100  feet  high,  where  its  course  is  bordered  by  a  bluff  of  till  so  steep 


Fig.  18.—  Section  across  channel  eroded  i 
cliannel  of  er( 

to  the  east  of  this  point. 


.  the  till ;  MmitTille. 


HARTLAIfD  MONTVILLB  SYSTEM. 


153 


as  to  suggest  tliat  it  has  been  eroded,  then  passes  Halldale  and  soon  ci-osses 
the  valley  of  the  south  branch  of  Half  Moon  Stream.  Here  it  expands 
into  a  plexus  of  reticulated  ridges  near  one-fourth  mile  wide  and  1  mile 
long.  Thus,  at  their  junction  these  two  glacial  rivers  must  have  behaved 
very  differently.  The  long  Hartland  glacial  river  swept  ever3'thing 
before  it  and  eroded  a  deep  channel  ui  the  till,  while  the  shorter  Free- 
dom River  deposited  a  very  large  amount  of  sediment.  For  some  reason 
the  waters  of  this  river  were  slowed  down  as  they  came  to  the  level 
ground  north  of  the  junction  of  the  two  glacial  rivers,  though  they  must 


T«r>  ,, 


Fig.  19. — Reticulated  ridges  and  Hogback  Mountain,  from  the  north. 

have  been  swift  to  the  north  of  this  place  in  order  to  have  swept  down 
so  much  gravel,  much  of  it  containing  cobbles  and  bowklerets.  South  of 
their  junction  I  have  not  been  able  to  distinguish  the  gravels  of  the  two 
streams. 

A  series  of  broad  and  somewhat  reticulated  ridges,  inclosing  kettle- 
holes  and  large  basins  containing  peat  swamps,  extends  southward  through 
the  Hogback  Mountain  Pass.  I'he  roadbed  occasionally  sinks  into  the 
peat  of  one  of  these  swamps.  The  pass  is  somewhat  more  than  a  mile 
long  and  less  than  a  fourth  as  broad.  At  the  south  end  of  the  pass  a 
short  hillside  esker  comes  down  the  slopes  of  the  hill  lying  on  the  east 
side  of  the  pass  and  joins  the  main  system  in  the  valley.     The  gravels 


154  GLACIAL  GRAVELS  OP  MAINE. 

at  the  south  end  of  the  pass  present  some  very  interesting  developments. 
The  east  branch  of  Georges  River  (or  St.  Greorges  River,  as  it  is  named 
on  many  maps)  rises  in  the  hills  east  of  Hogback  Mountain.  It  flows 
westward  to  the  south  end  of  the  Hogback  Mountain  Pass,  and  then 
south  and  east  through  ]\Iontville  and  Searsmont.  A  plain  of  gravel 
bowlderets  and  bowlders  (all  well  rounded)  extends  from  the  south  end 
of  the  pass  for  a  half  mile  down  the  valley.  The  material  is  coarse 
even  to  the  margins  of  the  plain.  Southward  in  this  valley  the  glacial 
gravel  is  scanty  and  discontinuous  for  about  2  miles  on  a  down  slope  of 
20  to  40  feet  per  mile,  yet  at  intervals  it  is  found  in  small  masses.  It  forms 
a  small  terrace  on  the  western  side  of  this  stream  at  Center  Montville, 
and,  becoming  more  abundant  toward  the  south,  soon  spreads  out  into 
a  rather  level  plain  2J  miles  long  and  more  than  1  mile  wide.  This  is 
situated  not  far  northwest  of  North  Searsmont.  Toward  the  south  the 
gravel  of  this  plain  passes  into  sand,  and  this  again  into  clay,  which 
extends  continuously  down  the  valley  of  Georges  River  to  the  sea.  This 
is  evidently  a  marine  delta,  and  seems  to  terminate  the  gravel  system 
in  that  direction. 

We  now  return  to  the  plain  of  coarse  glacial  gravel  at  the  south  end 
of  Hogback  Mountain  Pass.  This  deposit  is  somewhat  triangular  in  shape. 
One  apex  is  at  the  south  end  of  the  pass,  another'  extends  down  the  valley 
of  the  east  branch  of  Georges  River,  while  the  third  lies  in  a  depression 
along  the  southern  base  of  Hogback  Mountain,  about  one-half  mile  south- 
west of  the  first.  From  the  last-named  point  a  narrow  plain  of  glacial 
gravel  and  cobbles  extends  for  a  short  distance  southwest  along-  the  base 
of  the  "mountain."  The  Muskingum  Stream  drains  the  area  south  of  Hog- 
back Mountain  and  joins  the  west  branch  of  Georges  River  near  South 
Montville.  It  has  several  tributaries,  the  largest  two  of  which  I  will  call 
the  east  and  west  branches.  We  have  seen  that  the  osar  river  followed  the 
base  of  the  mountain  southwest  for  a  time.  By  turning  to  the  south  and 
crossing  a  col  only  20  or  30  feet  high,  it  might  have  flowed  south  along  the 
east  branch  of  the  Muskingum  Stream.  It  actually  rejected  this  pass,  and 
about  one-third  of  a  mile  farther  west  turned  southward  along  the  valley  of 
the  west  branch  of  Muskingum  Stream.  Within  3  miles  it  left  this  valley 
and  went  obliquely  southwestward  over  a  low  divide  into  the  valley  of  the 
east  branch  of  the  Muskingum  Stream,  the  same  valley  it  could  so  much 


5       -S 


HAKTLAl!fD-MONTVILLE  SYSTEM.  155 

more  easily  have  entered  at  the  sontlieru  base  of  Hogback  Mountain.  On  the 
down  slopes  in  this  part  of  its  course  the  system  is  somewhat  discontinuous. 
Near  where  the  system  enters  the  valley  of  the  east  branch  of  the  Muskin- 
gum Stream  it  expands  into  a  plain  of  reticulated  ridges,  wdth  an  outlying 
bar  directed  toward  the  southwest,  but  I  could  find  no  prolongation  of 
the  system  in  that  direction.  Just  north  of  this  plain  lies  a  narrow,  almost 
V-shaped,  valley,  bordered  by  rather  steep  cliffs  of  till.  No  ordinary  stream 
flows  in  the  valley,  except  the  merest  brook,  and  the  appearances  are  as  if 
the  glacial  river  had  here  eroded  the  till.  The  gravel  system  here  turns 
east  and  crosses  the  road  leading  up  the  valley  of  the  east  branch,  and  then 
becomes  a  prominent  feature  of  the  valley  southward  to  the  settlement  in 
Montville  known  as  the  "Kingdom,"  being  alternately  on  the  east  and  west 
sides  of  the  road.  The  gravel  appears  like  a  rather  level  terrace  at  the  side 
of  the  stream,  but  there  is  no  corresponding  terrace  on  the  east  side  of  the 
valley.  Well-rounded  bowlderets  and  bowlders  abound  in  the  gravel  and 
at  once  betray  the  glacial  origin  of  the  deposit.  Near  the  "Kingdom"  the 
gravel  expands  into  a  large  plain — the  Liberty  Plains — which  nearly  fills 
the  broad  level  valley,  in  the  midst  of  which  lies  Trues  Pond.  One  tongue 
or  expansion  of  these  plains  reaches  from  near  Libert}'  Village  southeast- 
ward almost  to  South  Montville,  but  the  principal  expansion  is  south  and 
west,  and  this  seems  again  to  divide  into  two  jjarallel  plains  inclosing 
between  them  Stevens  Pond  and  then  continuing  on  southwestward  through 
Liberty  into  Appleton.  Near  the  "Kingdom"  and  Liberty  Village  these 
plains  consist  of  broad  reticulated  ridges  of  very  coarse  matter,  inclosing 
kettleholes  and  even  lake  basins.  Southeast  toward  South  Montville  they 
become  rather  level  on  the  top  and  finer  in  composition,  while  the  long 
narrow  plains  which  extend  southwestward  into  Appleton  show  very  clearly 
the  transition  from  coarse  sediments  on  the  north  to  fine  on  the  south,  char- 
acteristic of  the  delta.  On  the  south  these  sand  plains  pass  by  degrees 
into  sedimentary  clay,  which  extends  all  the  way  down  the  Medomac  Val- 
ley to  the  sea.  The  more  level  portions  of  the  gravel-and-saud  plains  of 
Liberty  and  Appleton  are  thus  proved  to  be  marine  delta-plains.  In  the 
narrow  valley  of  the  west  branch  of  Georges  River  at  South  Montville  no 
sand  or  gravel  appears  for  about  one-fourth  of  a  mile.  Then  begins  a  delta- 
plain  extending  about  one-half  mile  eastward  toward  Searsmont,  and  then 
sending-  out  a  long-  tongue  southwestward  for  about  3  miles  into  Appleton. 


156  GLACIAL  GRAVELS  OF  MAINE. 

I  find  no  signs  of  any  glacial  streams  that  could  have  deposited  the  last- 
named  plain  except  that  delta  branch  of  the  Hartland  system  which  radiated 
southeast  from  the  "Kingdom;"  neither  could  I  trace  this  system  farther 
south  than  the  delta-plains  in  northern  Appleton. 

SUMMARY. 

The  Hartland-Montville  osar  river  must  have  deposited  its  gravels  late 
in  the  osar  period,  or,  like  the  Katahdin  and  other  osars,  it  would  have 
deposited  gravels  all  the  way  to  the  sea.  At  this  time  the  sea  stood  at  or 
near  the  contour  of  230  feet,  and  the  delta-plains  of  Libertj^  and  Appleton 
do  not  extend  much  below  that  elevation.  In  the  Sebasticook  Valley,  for 
about  20  miles,  from  Hartland  to  Unity,  the  system  traverses  a  region  that 
was  at  one  time  submerged  in  the  sea,  as  is  proved  without  a  shadow  of 
doubt  by  the  great  numbers  of  marine  fossils  found  in  the  sedimentary 
clays  which  partly  or  wholly  overlie  the  glacial  gravel.  But  at  the  time 
when  the  delta-plains  in  Liberty,  Appleton,  Searsmont,  and  Montville  were 
being  laid  down,  the  Sebasticook  Valley  must  have  beeu  covered  by  ice,  as 
is  proved  by  the  great  size  of  the  glacial  streams  by  which  only  could  so 
large  plains  be  deposited.  The  glacial  waters  of  the  Sebasticook  region 
then  poured  southward  through  the  Hogback  Mountain  Pass  over  a  divide 
not  far  from  200  feet  above  the  level  of  the  osar  at  Unity  Pond.  Into  the 
north  end  of  this  pass  two  glacial  rivers  flowed  from  the  north,  one  from 
Unity  and  Hartland,  the  other  from  Freedom.  At  the  south  end  of  the 
pass  the  system  received  another  tributary,  while  from  the  enlarged  chan- 
nel or  glacial  lake  at  that  point  two  delta  branches  diverged,  one  flowing 
south  and  the  other  southwest,  and  they  emptied  into  the  sea  at  jioints 
about  10  miles  distant  from  each  other.  The  narrow  delta-plains  in  Liberty 
and  Appleton  are  in  a  level  region,  where,  if  the  g'lacial  river  had  flowed 
into  the  open  sea,  they  ought  to  have  spread  out  in  fan  shape.  That  they 
remained  so  long  and  narrow  is  an  indication  that  they  were  not  deposited 
in  the  open  sea,  but  in  bays  of  the  sea  which  extended  back'iuto  the  ice. 
The  question  whether  a  stratum  of  floating  ice  was  over  these  plains  will 
be  considered  elsewhere.  The  plain  northwest  of  North  Searsmont  is  more 
broadly  fan-shaped.  Its  northern  end  extends  across  the  valley  of  Georges 
River,  and  the  delta  was  probably  deposited  in  the  open  sea. 

Did  the  two  glacial  rivers,  which  diverged  from  the  south  end  of  the 


HARTLAND-MONTVILLE  SYSTEM.  157 

Hogback  Mountain  Pass,  flow  simultaneously?  I  was  unable  to  find  any 
conclusive  facts  in  the  field.  Two  reasons  can  be  given  why  it  is  probable 
that  the  Liberty  bi'anch  was  the  earlier. 

1.  The  delta-plains  of  this  system  seem  to  date  from- a  time  when  the 
ice  had  not  receded  so  far  north  as  at  the  time  the  North  Searsmont  Plain 
was  being  deposited.  2.  The  glacial  stream  which  formed  the  last-named 
plain  flowed  not  only  down  a  valley  of  natural  drainage,  but  parallel  with 
the  direction  of  glacial  flow.  The  g-ravel,  too,  is  scanty  for  some  distance 
on  the  steep  down  slopes,  so  that  the  glacial  channels  did  not  there  become 
clogged  with  sediment.  I  see  no  reason  why  this  stream  should  cease  to 
flow,  or  why,  after  it  once  had  been  established,  it  should  not  carry  away 
all  the  water  that  poured  southward  through  the  pass.  On  the  other  hand, 
the  southwestern  channel  was  over  higher  ground,  and  for  a  time  was  trans- 
verse to  the  lines  of  flow  of  the  ice.  At  any  time  the  south  channel  should 
be  opened  this  stream  would  cease  to  flow,  except  possibly  when  the  water 
was  very  high.  The  history  of  the  gravel  plain  at  the  south  end  of  the 
pass  is  probably  about  as  follows:  Originally  the  glacial  river  flowed  by 
the  southwestern  channel  and  solid  ice  blocked  the  valley  of  the  east 
branch  of  Georges  River.  Then  a  lake  was  formed  within  the  ice  at  the 
south  end  of  the  pass,  in  which  was  deposited  the  coarse  matter  of  the 
plain,  or  a  part  of  it.  The  lake  gradually  enlarged,  so  as  finally  to  extend 
for  one-fourth  mile  or  more  eastward  into  the  valley  of  the  east  branch  of 
Georges  River,  which,  as  already  stated,  extends  eastward  from  the  south 
end  of  the  Hogback  Mountain  Pass.  In  this  enlarged  lake  was  deposited 
the  thick  sheet  of  sedimentary  clay  and  silt  which  covers  this  valley  to  the 
east  of  the  pass.  Finally  the  barrier  of  ice  in  the  valley  was  in  some  way 
penetrated  toward  the  south  and  a  new  channel  was  established  down  the 
valley  to  Center  Montville  and  to  the  sea  near  North  Searsmont.  This 
channel  would  naturally  come  to  be  lower  than  the  other,  so  that  it  would 
carry  off  all  the  water  of  the  glacial  lake,  except  in  times  of  great  floods, 
when  the  southwestern  channel  might  still,  for  a  time,  serve  as  an  overflow 
channel.  In  process  of  time  the  south  chamiel  would  become  enlarged  so 
as  to  take  off  all  the  water  by  the  lowest  route.  All  the  field  phenomena 
could  be  produced  by  two  streams  flowing  simultaneously.  But  much  the 
larger  stream  flowed  southwest,  and  it  deposited  far  more  gravel  than  the 
other.     These  facts  favor  the  conclusion  that  it  flowed  much  long-er  than 


158  GLACIAL  GRAVELS  OF  MAINE. 

the  other  stream.  If  the  two  channels  were  formed  simnkaneousl}^,  I  can 
conceive  no  reason  why  the  south  channel  on  a  down  slope  should  not 
enlarge  as  fast  as  the  southwestern  channel  on  an  iip  slope.  If  they  enlarged 
with  equal  rapidity,  the  larger  amount  of  sediment  ought  to  have  been 
deposited  by  the  eastern  instead  of  the  western  stream.  These  facts  all 
combine  to  justify  the  conclusion  that  the  diverging  delta  streams  were  for 
most  of  the  osar  period  not  simultaneous,  but  that  the  Liberty  branch  was 
the  earlier. 

During  the  final  melting  there  must  have  come  a  time  when  the  tliin- 
nmg  ice  could  no  longer  flow  southward  over  the  hills  and  when  the  supply 
of  glacial  water  from  the  north  would  be  diminished.  The  glacial  river 
flowed  sluggishly,  and  presently  in  the  osar  channel  northeast  of  the  north 
end  of  Hogback  Mountain  Pass  there  was  deposited  an  osar-plain  of  fine 
gravel  and  sand,  and  finally  clay.  As  the  ice  continued  to  melt,  the  ice 
front  began  to  retreat  northward  from  the  hills,  and  there  came  a  time  when 
a  lake  occupied  the  valley  of  Half  Moon  Stream.  This  valley  is  widely 
covered  by  a  sheet  of  sedimentary  clay  to  a  height  of  at  least  260  feet 
above  the  sea.  The  small  Half  Moon  Stream  could  not  have  deposited 
this  clay  as  ordinary  valley  alluvium,  for  it  reaches  at  least  30  feet  above 
the  stream.  The  most  probable  interpretation  is  that  in  Thorndike,  Knox, 
and  Unity  there  was  a  glacial  lake  several  miles  long  confined  between  the 
ice  on  the  north  and  the  hills  on  the  south,  east,  and  west.  It  may  not 
have  always  stood  at  the  same  height.  For  a  time  this  lake  may  have 
overflowed  south  through  Hogback  Mountain  Pass.  Into  the  lake  still 
poured  a  supply  of  glacial  water  from  the  north,  and  in  it  was  deposited 
the  delta-plain  situated  between  Unity  and  Thorndike  which  overlies  the 
ridges  previously  deposited  in  narrow  ice  channels  in  the  midst  of  the 
valley  of  Sand}^  Stream.  This  delta  reaches  from  near  Unity  Village 
almost  to  Thorndike  station.  But  in  the  meantime  the  sea  had  been 
advancing  up  the  valle3^s  of  the  Kennebec  and  thence  eastward  over  the 
broad  valley  of  the  Sebasticook  River.  If  it  first  advanced  along  the  south 
side  of  the  high  hills  which  border  the  Sebasticook  Plain  on  the  south, 
then  it  might  be  that  the  extreme  northern  part  of  the  delta-plain  south  of 
Unity  Village  was  deposited  in  the  sea.  With  possibly  this  exception,  the 
advance  of  the  sea  was  so  simultaneous  over  the  Sebasticook  Plain  that  no 
marine  deltas  were  formed  by  this  glacial  river  in  that  part  of  the  State, 


CAMBRIDGE  HARMONY  GRAVELS.  159 

unless  the  plain  in  Cambridge  and   Harmony,  soon  to  be  described,  was 
formed  by  a  remnant  of  this  glacial  river  which  still  continued  to  flow 
after  the  ice  m  the  main  Sebasticook  Valley  had  disappeared  but  while  the 
ice  still  lingered  north  of  Moose  Pond 
The  length  of  the  system  is  45  miles. 

CAMBRTDGE-HAKMONT   GRAVELS. 

A  sei-ies  of  low  sand-and-gravel  ridges,  or  narrow  plains,  extends  from 
near  Main  Stream  in  Cambridge  northward  past  Cambridge  Village  and 
then  for  2  or  3  miles  into  the  southwestern  part  of  Parkman.  The  stones 
are  barely  rounded  on  the  angles,  and  in  general  the  gravel  is  fine.  On  the 
south  the  series  spreads  out  inito  a  sand  plain  in  the  Main  Stream  Valley. 
This  plain  appears  to  have  been  deposited  in  the  valley  after  the  ice  had 
there  melted,  though  still  remaining  northward;  yet  the  sand  may  have 
been  laid  down  in  a  glacial  lake.  The  currents  which  assorted  these  sedi- 
ments were  rather  gentle,  and  j^robably  the  formation  dates  from  a  very  late 
portion  of  the  Glacial  period. 

Another  ridge  is  found  near  the  line  between  Harmony  and  Cambridge, 
ending  in  the  south  near  the  northern  shore  of  a  large  pond  above  Main 
Stream  Village.  Toward  the  south  the  material  becomes  fine,  consisting  of 
sedimentary  clay  overlying  fine  sand. 

A  short  gravel  deposit  is  found  near  Main  Stream  about  a  half  mile 
south  of  Main  Stream  Village. 

A  gravel  plain,  probably  glacial,  is  fomad  in  the  south  part  of  Har- 
mony, in  the  valley  of  a  small  stream.  It  resembles  an  osar-plain.  It  is 
possible  that  this  extends  northward  past  Harmony  Village.  I  have  note 
of  sand  and  clay  in  the  valley  of  the  Sebasticook  above  Harmony,  and  they 
may  be  of  glacial  origin  in  part. 

Probably  a  large  area  in  Cambridge,  Parkman,  Wellington,  and  Har- 
mony was  at  one  time  drained  of  its  glacial  waters  by  the  lai-ge  glacial  river 
which  flowed  from  Moose  Pond  south  past  Hartland.  But  if  so,  the  proof  is 
not  easily  derived  from  the  distribution  of  the  gravels.  The  gravels  in 
this  region  seem  to  date  from  a  late  period,  when  the  ice  had  retreated 
north  of  Moose  Pond,  and  the  glacial  streams  were  in  fact  soon  discharged 
beyond  the  ice  front  into  the  open  valleys. 


100  GLACIAL  GKAYELS  OP  MAINE. 

PALERMO-WARRteN    SYSTEM. 

This  system  begins  in  Palermo  near  where  the  towns  of  Palermo, 
Freedom,  and  Moutville  join.  Here  a  north-and-south  ridge  of  till  becomes 
more  stony  toward  the  south,  and  by  degrees  passes  into  unmistakable  gla- 
cial gravel  within  one-fourth  of  a  mile.  The  fact  that  the  glacial  gravel 
consists  of  the  till  with  the  finer  detritus  washed  out  of  it  is  here  well 
exhibited.  Near  the  east  branch  of  the  Sheepscot  River  this  ridge  turns 
southwestward,  and  follows  the  valley  for  several  miles.  This  stream  flows 
along  the  northern  base  of  the  high  northeast-and-southwest  range  of  which 
Hogback  Mountain  in  Montville  is  a  part.  Much  of  the  way  along  the 
valley  the  gravel  is  in  the  form  of  a  ridge,  but  it  becomes  terrace-like  and 
somewhat  discontinuous  as  it  approaches  Sheepscot  Great  Pond.  This 
pond  lies  in  the  midst  of  a  cirque  5  miles  in  diameter.  This  broad,  rather 
level  valley  is  surrounded  on  all  sides  by  rather  high  hills  except  at  a  few 
narrow  passes.  The  lowest  depression  is  southwest  down  the  valley  of  the 
east  branch  of  the  Sheepscot  River,  but  the  glacial  waters  rejected  the  valley 
of  natural  drainage  and  took  a  course  over  higher  ground  to  the  south  and 
southeast.  Two  lines  of  glacial  gravel  extend  from  Sheepscot  Great  Pond 
southward.  For  2  or  3  miles  they  are  nearly  parallel  and  only  from  one- 
fourth  to  one-half  mile  apart.  The  western  series  takes  the  form  of  an  osar- 
plain  one-eighth  to  one-fourth  mile  wide.  It  penetrates  a  low  pass  along 
the  western  base  of  the  high  granite  peak  called  Patrick  Mountain,  and 
continues  as  an  osar-plain  till  it  nears  Jones  Corner,  on  the  road  from 
Somerville  to  South  Liberty.  Here  it  takes  the  form  of  a  two-sided  ridge 
of  arched  cross  section  for  about  1  mile.  In  this  part  of  its  course  it  turns 
east  by  a  rather  abrupt  curve  and  then  closely  skirts  the  southern  base  of 
Patrick  Mountain.  In  so  doing  it  crosses  a  hill  about  75  feet  high,  the 
gravel  disappearing  for  one-third  of  a  mile  on  the  up  slope.  Near  the  top 
of  this  hill  it  takes  the  form  of  an  osar-plain  for  a  short  half  mile,  and  then, 
on  a  steep  down  slope,  there  is  no  gravel  for  near  1  mile  to  Branch  Stream, 
which  flows  south  into  Damariscotta  Great  Pond  at  East  Jefferson. 

We  now  go  back  to  the  swampy  plain  south  of  Sheepscot  Great  Pond 
in  the  midst  of  the  remarkable  Palermo  basin,  where  the  two  lines  of  glacial 
o-ravel  are  found  side  by  side.  The  more  eastern  of  the  two  formations  has 
the  form  of  a  broad  osar,  with  arched  cross  section.     It  soon  diverges  from 


PALE  LiMO- WARREN  SYSTEM.  161 

the  western  series  and  takes  a  southeast  course  throug-h  "The  Gore,"  a  por- 
tion of  land  unattached  to  any  town,  and  passes  around  the  northeastern 
base  of  Patrick  Mountain.  In  so  doing  it  goes  up  and  over  a  hill  100  feet 
high,  and  then  descends  into  the  valley  of  Branch  Stream,  where  it  turns 
soiTthward  and  soon  unites  with  the  series  which  diverged  from  it  near 
Sheepscot  Great  Pond  to  go  around  the  western  base  of  Patrick  Mountain. 
Except  on  the  steep  down  slopes  and  one  gap  on  an  up  slope,  the  gravels 
are  continuous  along  the  courses  here  indicated.  The  material  is  in  general 
rather  coarse,  many  cobbles,  bowlderets,  and  some  bowlders  being  mixed 
with  the  sand  and  gravel.  The  stones  are  all  very  round,  an  indication  that 
they  are  part  of  a  long  system,  not  of  a  local  one.  The  field  proof  is 
positive  that  these  large  glacial  rivers  diverged  from  each  other  so  as  to  go 
around  opposite  sides  of  a  high  hill  and  then  came  together.  In  both  cases 
we  find  little  or  no  gravel  on  down  slopes  of  from  50  to  100  feet  per  mile, 
but  it  is  certain  the  glacial  streams  came  from  the  north  to  the  top  of  the 
hills,  and  must  have  flowed  down  them;  and  at  the  base  of  the  liills  the 
gravel  begins  again.  It  is  a  fair  infereiace  that  on  the  steep  slopes  the 
glacial  streams  were  so  rapid  as  to  deposit  little,  if  any,  sediment. 

From  where  the  two  glacial  rivers  united,  in  the  valley  of  Branch 
Stream,  a  nearly  continuous  osar-plain  extends  southward  near  the  stream 
for  a  few  miles,  when  the  gravel  leaves  this  stream  and  takes  a  course  south- 
eastward, soon  expanding-  into  a  large,  somewhat  fan-shaped  plain,  situated 
not  far  southwest  of  Newhalls  Corner,  in  Washington.  This  plain  consists, 
toward  the  north,  of  broad  reticulated  ridges  inclosing  shallow  hollows. 
The  material  here  is  coarse.  Toward  the  south  the  plain  becomes  quite 
level  and  the  gravel  passes  into  sand  and  finally  into  the  marine  clay.  It 
is  2^  miles  long  and  more  than  a  mile  wide.  It  is  plainly  a  marine  delta, 
and  its  shape  is  such  as  to  make  it  probable  that  it  was  deposited  in  the 
open  sea,  possibly  in  a  very  broad  bay  of  the  ice.  Its  outlet  has  cut  down 
a  channel  100  or  more  feet  wide  to  a  depth  of  about  4  feet,  and  numbers  of 
ordinary  till  bowlders  are  exposed  where  the  gravel  has  been  removed. 
The  little  polishing-  they  may  have  received  from  the  gravel  has  been 
obliterated  by  weathering.  The  same  thing  is  observed  over  a  considerable 
area,  and  proves  conclusively  that  the  glacial  gravel  and  sand  overlie  the 
till  and  are  without  admixture  of  till;  hence  they  were  deposited  after  the 
xnelting  of  the  ice  at  this  place.     The  outlet  of  the  lake  above  described 

MON  XXXIV 11 


1C2  GLACIAL  GRAVELS  OF  MAINE. 

flows  southward.  In  the  soiitlieast  part  of  the  plain  the  gravel  is  deeper 
and  has  been  eroded  considerably  by  boiling  springs.  A  ravine  10  feet 
deep  has  been  eroded  back  into  the  plain  for  one-fonrth  of  a  mile  or  more. 
In  many  places  this  delta-plain  is  overlain  to  the  depth  of  1  to  3  feet  with 
marine  clay.  From  this  point  southward  the  system  is  discontinuous  and 
consists  of  short  ridges,  lenticular  mounds,  and  round-topped  plains,  except 
a  delta-plain  at  its  south  end.  The  gravels  are  separated  by  intervals  of 
from  one-eighth  to  one-half  of  a  mile,  generally  the  shorter  distance.  It  is 
specially  noticeable  in  case  of  the  southern  part  of  this  system  that  the 
gravels  appear  on  the  tops  of  low  hills  or  at  the  brow  of  broad  hills,  while 
the  lowlands  show  little  or  no  gravel.  The  series  crosses  Medomac  Pond, 
and  thence  its  course  is  easily  followed  along  the  road  from  North  Waldo- 
boro  to  Warren.  At  the  western  edge  of  the  valley  of  the  Warren  ponds 
the  system  divides  into  two  series.  One  crosses  to  the  east  side  of  the 
valley  at  once,  the  other  follows  the  eastern  brow  of  the  hills  which  border 
this  valley  on  the  west.  In  a  mile  or  two  this  series  also  crosses  to  the  east 
side  of  the  valley,  and  then  takes  a  course  nearly  parallel  with  the  other 
series.  They  pass  southward,  and  not  far  southeast  of  Warren  station  they 
end  in  sand  plains.  For  the  last  mile  or  two  they  are  quite  continuous  and 
form  plains  one-eighth  to  one-fourth  mile  wide,  and  hence  resemble  the 
parallel  jjlains  of  Liberty  and  Appleton.  Their  shapes  and  their  situation 
on  the  tops  of  hills  prove  that  they  were  deposited  within  ice  walls,  or  the 
gravel  would  have  spread  out  into  broad  fan-shaped  plains.  The  discon- 
tinuous portion  of  this  system — that  part  where  gaps  form  a  constant 
feature  of  the  system,  not  an  occasional  gap  on  a  steep  down  slope — is 
noticeable  for  the  large  amount  of  gravel  which  it  contains,  the  lenticular 
plains  which  cap  the  hills  being  larger  than  the  average.  In  the  valley  of 
Georges  River  and  the  Medomac  above  Waldoboro  the  gravels  are  in  or 
near  the  lowest  parts  of  the  valley.  But  in  general  this  system  seems  to 
delight  in  the  highest  ground  that  lies  in  its  course,  leaving  the  low  valleys 
for  the  gaps. 

Two  or  three  short  tributaries  entered  the  main  glacial  river  near 
Sheepscot  Great  Pond.  They  drained  the  large  Palermo  cirque.  Their 
gravels  are  but  little  water  polished,  and  they  are  evidently  only  short 
branches  of  the  m^ain  system. 

Length  from  Palermo  to  Warren,  23  miles. 


MEDOMAC  VALLEY  SYSTEM.  163 

SHORT   ESKEES   IN   WALDOBORO. 

Two  small  and  rather  level  plains  of  sand  and  gravel  are  fonnd  a 
short  distance  south  of  the  terminal  moraine  in  Waldoboro,  elsewhere 
described,  one  on  the  road  from  Waldoboro  to  North  Waldoboro,  the 
other  about  half  a  mile  east  of  this  on  the  road  to  Union.  Both  seem 
to  be  small  marine  delta-plains.  Their  north  ends  lie  a  short  distance 
south  of  the  terminal  moraine,  but  thus  far  I  can  not  connect  them  with 
this  moraine  in  a  genetic  way.  The  marine  clay  covers  the  deposits  on 
the  flanks  and  makes  it  difficult  to  trace  the  connections  of  these  sands. 

MEDOMAC    VALLEY    SYSTEM. 

This  system  begins  in  the  valley  of  the  Medomac  River  about  2 
miles  north  of  Winslows  Mills,  and  extends  southward  to  Waldoboro 
Village.  For  most  of  this  distance  its  course  is  near  the  stream  in  the 
lower  part  of  the  valley.  The  series  consists  of  short  ridges  and  elongated 
mounds,  or  sometimes  more  nearly  cones,  separated  by  intervals  of  one- 
eighth  to  one-third  of  a  mile,  and  is  discontinuous  from  one  end  to  the 
other.  None  of  the  deposits  are  more  than  about  20  feet  high,  and  many 
of  them  are  much  lower.  They  are  often  covered  wholly  or  in  part  by 
the  marine  clay.  Toward  the  north  end  of  the  series  the  gravel  is  but 
little  waterworn,  and  at  the  last  can  hardly  be  distinguished  from  a  sandy 
till.  The  relations  of  this  gravel  system  to  the  terminal  moraine  at 
Winslows  Mills  will  be  referred  to  hereafter. 

Length,  about  5  miles. 

LOCAL   GRAVELS   IN   N03LEB0R0   AND   .JEFFERSON. 

A  gravel  ridge  comes  from  the  north  and  enters  the  so-called  Great 
Bay  at  East  Jefferson.  It  can  readily  be  traced  northward  up  a  hill  for 
about  a  mile,  where  it  seems  to  end  in  a  low  pass.  To  the  north  of  this 
pass,  in  the  northern  part  of  Jefferson,  is  a  short  ridge  of  subangular  glacial 
gravel,  but  I  could  trace  no  evident  connections  southward.  Gravels  are 
reported  at  various  points  along  the  Damariscotta  Great  Pond,  but  I  am 
uncertain  whether  they  are  old  beaches  or  not.  Near  Muscongus  Bay 
station  of  the  Maine  Central  Railroad  is  a  small  plain  of  glacial  gravel. 
Another   appears   about  one-fourth  of  a  mile  farther   south,  and  a  third 


164  GLACIAL  GRAVELS  OF  MAINE. 

within  a  mile  farther,  near  Nobleboro  Post-Office.  The  three  gravel  plains 
south  of  Muscongus  Bay  have  a  linear  arrangement;  probably  they  all  are 
deltas,  and  they  may  have  been  deposited  by  the  same  glacial  stream. 
Whether  they  are  connected  with  the  East  Jefferson  gravels  is  uncertain. 
Two  other  small  gravel  plains  are  found  in  Nobleboro  north  of  Duckpuddle 
Pond.  A  small  ridge  of  glacial  gravel  is  found  near  the  west  shore  of 
Damariscotta  Great  Pond,  about  3  miles  north  of  the  south  line  of  Jeffer- 
son; and  3  iniles  farther  north  another  small  ridge  is  found  on  an  east-and- 
west  road.  All  of  these  local  gravels  are  found  in  a  region  that  was  under 
the  sea.  Old  beaches  abound  in  the  same  region,  and  it  requires  some  care 
to  distinguish  the  glacial  from  the  beach  gravel. 

DYERS  RIVER  SYSTEM. 

A  very  discontinuous  system  seems  to  begin  in  Jefferson,  west  of 
Dyers  Long  Pond,  and  extends  southward  about  4  miles  along  the  valley 
of  Dyers  River.  It  then  passes  obliquely  out  of  the  valley  southeastward 
into  a  rolling  plain  near  100  feet  above  the  stream,  and  appears  to  end  near 
Great  Meadow  River  in  Newcastle.  So  far  the  system  is  pretty  well 
defined.  About  2  miles  from  the  north  end  of  the  system,  as  above 
described,  are  two  short  gravel  ridges,  and  a  mile  farther  north,  at  West 
Jefferson,  is  a  gravel-and-sand  plain  one-half  mile  long  and  a  full  eighth 
of  a  mile  wide.  This  is  probably  a  marine  or  lake  delta.  A  trotting  track 
has  been  made  on  it.  One  mile  northwest  of  West  Jefferson  are  two  short 
but  good-sized  ridges,  and  2  miles  north  of  them  are  two  small  ridges,  in 
the  valley  of  the  west  branch  of  the  Sheepscot  River.  Two  miles  farther 
north  is  a  small  gravel  deposit,  near  Coombs's  store  in  Windsor.  All  of 
these  last-named  gravel  deposits  have  a  linear  arrangement  and  are  situated 
along  a  route  level  enough  for  the  passage  of  a  glacial  river  without  its 
having  to  cross  hills  higher  than  about  100  feet,  but  the  gaps  between  the 
gravels  are  so  long  and  the  deposits  so  small  that  it  is  uncertain  whether 
they  were  deposited  by  the  same  glacial  stream.  Most  of  the  deposits  of 
Dyers  River  system,  as  well  as  the  very  widely  separated  gravels  north  of 
them,  are  situated  on  the  tops  of  hills,  or  on  their  flanks,  50  or  more  feet 
above  the  adjacent  valleys.     The  gravel  is  all  pretty  well  rounded. 

Its  leno'th  is  12  miles. 


SYSTEMS  OF  GLACIAL  GRAVELS.  165 

SOUTH    ALBION-CHINA    SYSTEM. 

About  2  miles  east  of  South  Albion  (Puddledock),  at  the  northern 
base  of  the  high  hills  which  border  the  Sebasticook  Plain  on  the  south,  is 
a  plain  one-fourth  mile  long  and  more  than  half  as  wide.  It  contains 
many  well-rounded  bowlderets  and  bowlders  2  to  3  feet  in  diameter.  On 
all  sides  it  ends  in  a  bluff  20  to  30  feet  high.  To  the  north  is  the  gently 
rolling  plain  of  the  Sebasticook  Valley,  covered  for  many  miles  with 
marine  clays.  I  could  find  no  similar  deposits  to  the  north  or  east  of  this 
plain.  A  series  of  similar  broad  level-topped  plains,  separated  by  short 
intervals,  extends  southwest  of  this  point  along  the  northern  base  of  the 
hills,  at  a  height  of  50  to  75  feet  above  the  clay  plain.  Some  of  these 
plains  are  bordered  on  both  sides  by  steep  banks;  others  were  deposited 
against  the  side  of  the  hill  as  terraces.  These  plains  present  a  curious 
alternation  of  areas  of  coarse  gravel,  containing  bowlderets  and  bowlders, 
with  areas  of  sand,  as  if  these  were  a  series  of  deltas  deposited  in  bi'oad 
channels  in  the  ice  which  were  practically  glacial  lakes.  The  terraces 
become  narrow  near  South  Albion.  From  this  point  for  several  miles  they 
are  in  a  narrow  valley  in  which  a  branch  of  Fifteenmile  River  flows  north- 
east to  South  Albion.  Usually  the  gravel  takes  the  form  of  ten-aces  on 
the  east  side  of  this  valley,  while  one-fourth  of  a  mile  distant  on  the  oppo- 
site side  of  the  valley,  or  often  less  than  half  that  distance,  are  a  large 
number  of  morainal  heaps  and  ridges.  In  several  places  the  appearances 
are  as  if  a  glacial  stream  flowed  through  the  valley  while  the  ice  was  still 
thick.  Then  later  a  narrow  and  thinner  tongue  of  ice,  practically  a  local 
glacier,  lingered  for  a  time  in  the  valley,  and  at  this  time  the  glacial  river 
assorted  the  moraine  stuff  that  was  cast  down  on  the  east  side  of  the  valley, 
while  on  the  west  side  the  lateral  moraine  retained  its  pellmell  structure. 
These  heaps  of  till  may  be  in  part  the  terminal  moraines  of  the  hypotheti- 
cal local  glacier  formed  during  its  retreat  northward.  If  these  peculiar 
masses  of  till  are  not  due  to  a  local  movement,  as  suggested,  they  are  a 
strange  freak  of  the  general  movement. 

In  the  southwestern  part  of  Albion  the  system  crosses  a  very  low  divide 
and  continues  straight  on  through  China  to  the  northeastern  base  of  Par- 
menter  Hill.  It  here  turns  abruptly  westward  and  skirts  the  north  and 
west  bases  of  this  high  hill,  taking  the  form  of  a  naiTow  plexus  of  two  or 


166  GLACIAL  GKAVELS  OF  MAINE. 

three  ridges  inclosing  numerous  kettleholes  and  one  or  two  lake  basins. 
The  ridges  become  broader  toward  the  south  and  coalesce  into  a  level  plain 
of  sand,  which  ends  near  the  road  from  Branch  Mills  to  China  Village. 
Within  a  short  distance  the  gravels  l^egin  again  and  continue  in  a  nearly 
straight  line  southwestward,  ending  about  one-fourth  of  a  mile  south  of 
Weeks  Mills,  in  the  southeastern  part  of  China.  For  several  miles  the 
gravels  are  in  the  form  of  a  long  plain  one-fourth  mile  or  less  in  breadth. 
Near  Weeks  Mills  the  plain  consists  of  one  or  more  ridg-es  of  arched  cross 
section,  flanked  and  sometimes  covered  by  fine  gravel  and  sand,  and  the 
plain  is  bordered  by  sedimentary  clay,  which  extends  down  the  Sheepscot 
Valley  to  the  coast. 

The  structure  of  the  plain  indicates  that  a  ridge  was  first  formed  in  a 
narrow  channel  within  the  ice.  Subsequently  a  marine  or  estuarine  delta- 
plain  was  deposited  in  a  broad  channel  open  to  the  sea  to  the  south,  but 
still  confined  between  ice  walls  at  the  sides.  In  some  respects  tliis  delta- 
plain  resembles  the  osar-plain  in  its  form  and  relations  to  the  central  ridge, 
but  in  this  case  the  original  ridge  was  less  modified  than  is  usually  the  case 
in  the  osar-plain,  so  that  the  distinction  between  it  and  the  bordering  plain 
is  quite  sharply  defined. 

This  system  is  remarkable  for  its  large  size  at  tlie  extreme  north  end. 
This  indicates  a  northward  extension  of  the  system,  but  I  have  not  been  able 
to  find  any.  The  country  is  so  deeply  covered  by  the  marine  clay  that  large 
gravel  ridges  might  exist  beneath  the  clay  and  not  attract  attention.  Sev- 
eral ridges  and  mounds,  probably  of  glacial  gravel,  are  found  near  the  east 
base  of  Parmenter  Hill,  and  they  may  be  a  connection  of  this  system. 

The  large  size  of  the  bowlders  contained  in  the  gravel  plains  at  the 
north  end  of  this  system,  together  with  their  topographical  relations,  suggest 
that  they  were  formed  at  the  front  of  a  mass  of  moving  ice.  Several  other 
facts  support  the  same  conclusion: 

1.  This  glacial  river  formed  a  marine  delta  in  the  southern  part  of 
China,  40  miles  or  more  from  tide  water,  at  an  elevation  of  about  200  feet, 
and  there  is  no  proof  that  it  at  any  time  flowed  farther  south.  It  must 
have  been  pretty  late  in  glacial  time  Avhen  the  ice  had  melted  so  far  north 
as  this. 

2.  As  before  noted,  the  ice  could  no  longer  flow  south  over  the  hills 


SOCTTH  ALBION-CHINA  SYSTEM.  167 

which  extend  nearly  east  and  west  from  Albion  and  Palermo  to  Newburg 
after  it  became  less  than  500  or  800  feet  thick.  About  the  same  time  that 
the  flow  was  arrested  here  it  wotild  be  arrested  by  another  east-and-west 
line  of  hills  situated  about  30  miles  farther  north  (those  lying  south  of 
the  Piscataquis  Valley).  The  broad  level  valley  of  the  Sebasticook  would 
be  filled  by  a  sheet  of  ice  sloping  south,  and  it  would  for  a  time  send  out 
projecting  tongues  over  the  lower  cols.  One  of  the  lowest  of  these  passes 
is  that  which  is  followed  by  the  South  Albion-China  system  of  gravels. 

3.  Since  at  this  time  the  melting  waters  could  escape  only  by  the  low 
passes,  they  collected  near  the  hills  and  then  flowed  east  or  west  till  they 
found  an  exit.  This  water,  being  exposed  to  the  sunlight,  would  melt  the 
ice  rapidly  near  the  base  of  the  hills  which  lay  as  a  barrier  to  the  south, 
and  thus  considerable  sized  pools  or  channels  might  be  formed.  The  glacial 
streams  from  the  north  would  flow  into  these,  and  at  the  same  time  there 
was  a  limited  flow  from  the  north  of  the  ice.  Thus  the  matter  brought 
down  by  the  glacial  streams  would  be  mixed  with  matter  brought  to  the 
edge  of  the  pool  by  the  moving  ice  and  subsequently  dximped  into  the  pool 
by  the  melting  of  the  ice  that  held  it.  On  this  hypothesis  the  plains  which 
lie  along  the  northern  bases  of  the  hills  near  South  Albion  are  a  mixture  of 
water-washed  moraine  and  ordinary  kame  matter. 

The  local  conditions  at  South  Albion  certainly  favor  a  flow  of  ice  to 
this  point  until  very  nearly  all  the  ice  was  melted.  The  valley  of  Fifteen- 
mile  River  narrows  toward  the  southwest  so  as  to  converge  the  movements 
into  the  narrow  pass.  A  very  small  motion  of  the  separate  particles  of  ice 
over  the  broad  plain  stretching  30  miles  northward  would  cause  a  con- 
siderable movement  in  the  narrow  valley.  The  ice  there,  being  crowded 
against  the  hills,  would  not  form  a  glacial  lake  extending  from  the  hills 
back  to  a  considerable  distance  northward.  But  the  glacial  motion  could 
bring  forward  moraine  stuif  and  throw  it  down  into  the  broad  channels  and 
pools  of  the  glacial  river  which  drained  the  ice  field  lying  to  the  north. 

There  are  several  enlargements  of  the  delta-plain  in  China  which  are 
somewhat  fan-shaped  but  not  broad.  They  may  indicate  a  gradual  reces- 
sion of  the  ice  before  the  sea  and  the  formation  of  a  series  of  small  deltas 
in  the  open  sea,  or  perhaps  frontal  deltas. 

The  length  of  the  system  is  about  15  miles. 


168  GLACIAL  GRAVELS  OF  MAINE. 

CLINTON-ALNA    SYSTEM. 

This  notable  gravel  system  appears  to  begin  in  the  southeast  part  of 
Canaan.  It  takes  its  course  to  Clinton  Village  by  a  line  which  in  general 
is  quite  straight,  but  has  many  minor  meanderings.  It  is  here  a  nearly 
continuous  osar.  At  Clinton  it  turns  southwest  and  follows  the  valley  of 
the  Sebasticook  River  for  about  3  miles,  and  here  it  is  somewhat  discontin- 
uous, either  because  it  was  so  deposited  or  on  account  of  erosion  by  the 
river.  About  halfway  between  Clinton  Village  and  Benton  Falls  the 
gravel  leaves  the  valley  of  the  Sebasticook  and  turns  southward  over  a 
rolling  country  in  Benton,  Winslow,  and  Albion,  being  osar-like  in  form, 
but  with  several  gaps  at  long  intervals.  From  China  southward  the  series 
becomes  conspicuously  discontinuous,  the  short  ridges  being  separated  by 
intervals  up  to  more  than  a  half  mile  in  length.  The  system  follows  the 
west  shore  of  China  Pond,  passing  a  short  distance  west  of  South  China, 
and  at  Chadwicks  Corner,  in  the  south  part  of  China,  expands  into  a  plain 
near  a  mile  long  and  more  than  half  as  broad.  This  plain  ends  in  a  rather 
steep  bank  on  all  sides.  A  well  73  feet  deep,  dug  at  a  point  on  the  slope  of 
the  plain,  and  probably  50  feet  below  the  top,  did  not  penetrate  the  sand 
and  gravel.  Overlying  this  plain  is  a  scattered  drift  closely  resembling 
till  and  containing  many  bowlders  of  shapes  characteristic  of  the  till.  South 
of  this  point  is  a  series  of  lenticular  domes  separated  by  the  usual  intervals; 
then  a  broad  plain  near  a  half  mile  wide  extending  from  West  Windsor  to 
a  point  2  miles  south  of  Windsor  Village.  This  plain  is  rather  level  on 
the  top,  except  that  here  and  there  are  shallow  basins  and  one  deep  lake 
basin.  These  plains  are  everywhere  covered  at  the  base  by  the  marine 
clays,  and  are  sprinkled  on  the  tops  and  flanks  by  angular  bowlders.  The 
same  sort  of  bowlders  are  scattered  over  the  clays,  though  not  so  abun- 
dantly as  on  the  higher  gravel  hills.  They  are  probably  of  ice-floe  origin. 
In  Whitefield  the  gravel  takes  the  form  of  a  discontinuous  series  of  short 
narrow  ridges  separated  by  numerous  intervals  of  the  usual  length.  It 
approaches  the  Sheepscot  River  near  North  Whitefield,  follows  this  valley 
for  several  miles,  and  then  in  the  southern  part  of  Whitefield  and  northern 
part  of  Alna  it  expands  into  a  delta-like  plain  three-fourths  of  a  mile  in 
breadth  and  nearly  twice  that  length.  This  plain  is  situated  on  the  tops  of 
the  hills,  50  to  100  feet  above  the  Sheepscot  River.     South  of  this  plain 


CLTNTON-ALNA  SYSTEM.  ■       169 

there  is  an  interval  of  a  mile  or  more  without  gravel,  and  then  a  discontin- 
uous series  of  short  and  not  very  broad  ridges,  which  extends  from  Alna  Post- 
Office  (Head  of  the  Tide)  southward  to  Sheepscot  Bridge,  lying  most  of  the 
way  along  a  valley  situated  west  of  the  Sheepscot  River.  A  short  distance 
noi'th  of  Sheepscot  Bridge  the  glacial  river  turned  abruptly  east  and  flowed 
up  and  over  a  hill,  and  then  descended  into  the  valley  of  the  Sheepscot 
River,  where  the  gravel  becomes  a  little  broader.  Thence  a  series  of  low 
mounds  and  short  ridges  is  found  near  the  river  to  a  point  about  half  a 
mile  south  of  Sheepscot  Bridge,  where  the  system  ends  at  the  shore  of 
Shee23Scot  Bay.  Like  many  other  systems,  the  mounds  of  gravel  become 
smaller  toward  the  south.  I  explored  the  country  in  Newcastle  and  Edge- 
comb  lying  south  of  where  the  system  disappears.  There  are  many  old 
beaches  in  the  region,  but  no  glacial  gravels  were  found. 

At  three  places  this  large  glacial  river  deposited  deltas  in  the  sea. 
These  are  situated  near  the  line  between  Alna  and  Whitefield,  in  the  cen- 
tral part  of  Windsor,  and  possibly  another  at  Chadwicks  Corner,  in  the 
south  part  of  China.  Perhaps  near  the  top  of  the  hills  in  the  southern  part 
of  Clinton  the  system  was  above  the  sea,  but  in  all  the  rest  of  its  course  it 
lies  in  a  country  covered  by  the  marine  clays.  No  system  in  the  central 
part  of  the  State  contains  so  much  gravel  as  this. 

Its  length  is  45  or  more  miles. 

ALBION   BRANCH. 

A  series  of  short  ridges,  separated  by  intervals  of  half  a  mile  to  more 
than  a  mile,  begins  about  IJ  miles  northwest  of  Albion  Village,  and  takes 
a  course  south  and  west  to  join  the  main  system  about  a  mile  north  of 
China  Village.  Toward  the  north  the  gravel  is  but  little  water  washed ;  so 
the  series  probably  does  not  extend  far  in  that  direction. 

WINSLOW-WINDSOR  BRANCH. 

A  discontinuous  series  of  short  ridges  begins  about  a  mile  south  of  the 
Sebasticook  River  in  Winslow  and  extends  southward  along  the  crest  of 
the  hills  bordering  the  valley  of  Outlet  Stream  on  the  east.  It  thence 
extends  southward  past  East  Vassalboro  and  near  the  northeast  angle  of 
Webber  Pond;  thence  southeastward  to  the  head  of  Threemile  Pond; 
thence  across  this  pond  and  in  nearly  a  straight  line  to  a  point  about  2 
miles  north  of  Windsor  Village,  where  it  joins  the  main  system. 


170  GLACIAL  GRAVELS  OF  MAINE. 

This  series  penetrates  a  rather  level  region  and  does  not  cross  hills 
more  than  about  100  feet  high.  For  its  whole  course  it  has  been  under  the 
sea,  and  its  bases  are  flanked  and  more  or  less  covered  by  clay,  often  con- 
taining great  numbers  of  marine  fossils.  The  clay  is  more  abundant  along 
the  line  of  the  gravels  than  away  from  it  on  ground  as  favorably  situated 
for  the  deposition  of  sediment  by  the  sea.  At  the  south  end  of  Three- 
mile  Pond,  in  Windsor,  I  had  some  difficulty  in  tracing  the  course  of  the 
osar  river,  as  no  gravel  appeared  on  the  surface.  But  passing  obliquely 
up  the  hill  at  the  south  end  of  the  pond  was  a  belt  about  one-eighth  of  a 
mile  wide  which  was  free  from  bowlders,  whereas  there  was  a  considerable 
number  of  bowlders  on  each  side.  Examination  of  the  ravines  of  erosion 
on  the  hillside  showed  that  here  was  a  strip  of  clay  much  deeper  than  the 
marine  clay  on  each  side,  which  was  not  thick  enough  to  conceal  the 
larger  bowlders  of  the  till.  Going-  southward  along  the  line  of  thick  clays, 
the  glacial  gravels  soon  reappear,  and  plainly  underlie  the  clay.  I  infer 
that  the  gravels  were  first  deposited  in  a  rather  narrow  channel  in  the  ice. 
This  channel  was  subsequentl}^  greatly  enlarged,  although  still  bordered 
by  ice  walls.  In  this  broad  channel  kame  border  clay  was  deposited.  In 
the  southern  part  of  Vassalboro,  not  far  from  Webber  Pond,  a  fine  blue 
clay,  apparently  the  kame  border  clay,  is  highly  fossiliferous.  Finally  the 
ice  all  melted  and  the  whole  region  lay  beneath  the  sea.  A  thin  sheet  of 
purely  marine  clay  was  now  spread  over  the  kame  border  clay  and  all  the 
previously  deposited  drift. 

At  several  points  along  the  line  of  this  series  short  ridges  are  found 
at  right  angles  to  the  main  ridge.  These  were  probably  deposited  by 
small  tributary  streams,  yet  in  some  cases  they  ma}"  be  due  simply  to 
an  abrupt  enlargement  of  the  main  channel.  Near  the  line  of  this  series 
are  a  number  of  pinnacles  and  cones  of  till  of  quite  irreg'ular  shape,  which 
are  more  fully  described  elsewhere.  Wells  dug-  along  the  line  of  this 
series  show  that  in  general  the  sedimentary  clay  ovei'lies  the  gravel.  One 
well  in  Windsor,  near  the  junction  of  this  glacial  stream  with  the  main 
river,  is  dug  through  gravel  into  fine  blue  clay.  Whether  the  gravel  Avas 
deposited  in  this  position  by  the  glacial  stream,  or  was  washed  down  upon 
the  clay  by  the  waves  of  the  sea,  is  uncertain. 

The  length  of  the  branch  is  14  miles. 


SYSTEMS  OF  GLACIAL  GEAYELS.  171 


LOWER    KENNEBEC    VALLEY    SYSTEM. 


The  northern  connections  of  ihis  system  are  not  explored,  and  they 
may  extend  into  Harmony  and  WeUington,  and  perhaps  farther.  A  gravel 
plain  about  one-half  mile  in  diameter  is  found  in  the  southwestern  part 
of  Harmon}^  and  southeastern  part  of  Athens.  Thence  a  discontinuous 
series  of  low  bars  and  terraces  extends  several  miles  southwestward  along 
a  low  pass.  In  places  the  appearance  is  as  if  an  osar-plain  had  been 
eroded  so  as  to  leave  fragments  of  its  former  self  here  and  there,  but  in 
general  the  gravel  seems  to  have  been  originally  deposited  discontin- 
uously.  In  the  southeastern  part  of  Cornville  the  gravel  takes  the  form 
of  a  ridge,  which  extends  nearly  continuously  through  Canaan  Village  and 
thence  southwestward  through  Clinton.  It  crosses  the  Kennebec  River 
a  short  distance  north  of  Somerset  Mills  and,  as  a  continuous  osar,  follows 
the  west  side  of  the  river  through  Fairfield  Village  and  Waterville,  below 
which  place  it  becomes  regularly  discontinuous.  Near  Riverside,  in  Vas- 
salboro,  the  series  again  crosses  the  Kennebec,  and  is  found  on  the  east 
side  of  the  river  through  most  of  Augusta.  In  Hallowell  and  Cardiner 
the  ridges  are  again  found  on  the  west  side  of  the  river.  At  Soxith 
Gardiner  the  system  crosses  to  the  east  side  again,  and  continues  on  that 
side  through  Pittston  and  Dresden,  expanding  into  a  broad  plain-like 
ridge  or  terrace  opposite  Richmond  Village.  This  plain  is  a  delta  of  some 
sort,  but  under  what  conditions  it  was  laid  down  I  have  not  determined. 
South  of  this  point  the  gravels  are  increasingly  discontinuous.  Glacial 
gravel  appears  at  three  places  on  the  east  side  of  Swan  Island  (Perkins 
Plantation);  also  at  Abagadassett  Point,  in  Bowdoinham,  at  the  head  of 
Merrymeeting  Bay,  the  broad  body  of  fresh  water  or  lake  into  which  the 
Kennebec  and  Androscoggin  rivers  flow. 

At  South  Gardiner  and  near  Iceboro  the  gravels  of  this  system  form 
small  islands  in  the  Kennebec  River.  The  largest  plain  in  the  whole  system 
is  the  one  near  Moose  Pond,  in  the  southwest  part  of  Harmony,  at  the  north 
end  of  the  system  as  here  described.  At  this  point  a  glacial  stream  flowed 
into  either  a  glacial  lake  or  the  sea.  It  is  not  easy  to  determine  the  height 
of  the  sea  in  the  vicinity  of  Moose  Pond.  Clays  plainly  marine  extend 
up  the  Sebasticook  Valley  to   Palmyra,  where  marine  fossils  are  found. 


172  GLACIAL  GRAVELS  OF  MAINE. 

Sedimentary  clays  of  uncertain  origin  extend  up  the  Sebasticook  to  near 
Hartland  Village,  not  far  from  the  southeast  end  of  Moose  Pond.  From 
the  southwest  angle  of  the  same  pond  a  strip  of  sedimentary  clay  one-eighth 
to  one-half  of  a  mile  wide  is  found  along  the  line  of  the  glacial  gravel  south 
and  west  through  Cornville  into  Canaan,  where  they  are  plainly  marine.  A 
line  of  clays  is  also  said  to  extend  from  Canaan  eastward  into  Hartland. 
These  facts  prove  that  clay  extends  continuously  up  to  the  elevation  of 
Moose  Pond,  244  feet.  The  marine  fossils  in  Palmyra  have  an  elevation 
of  215-230  feet.  It  will  be  an  interesting  problem  to  determine  how  far 
the  marine  clay  extends  and  where  the  kame  border  or  the  fluviatile  clay 
begins,  for  the  clays  along  the  line  of  the  gravel  system  in  Corn^^lle  may 
have  been  deposited  in  a  broad  channel  in  the  ice.  The  delta-plain  near 
the  west  end  of  Moose  Pond  is  two  or  three  times  as  broad  from  west  to 
east  as  from  north  to  south.  The  coarsest  matter  is  on  the  north;  hence  the 
streams  flowed  from  that  direction. 

In  Corn^alle  and  Canaan  both  the  gravel  system  and  the  bordering 
clays  are  strewn  with  numbers  of  large  granite  bowlders.  Similar  bowlders 
overlie  the  marine  clays  all  the  way  to  the  sea,  and  they  are  probably  floe 
bowlders. 

From  Waterville  to  Bowdoinham  the  gravels  of  this  system  lie  along 
the  Kennebec  River,  or  only  a  short  distance  from  it.  The  road  gravel  of 
Augusta,  Hallowell,  and  Gardiner  comes  from  this  series.  In  a  few  places 
the  mounds  and  short  ridges  form  hills  50  to  70  feet  high,  and  some  of 
them  form  a  conspicuous  feature  of  the  scenery  of  this  beautiful  valley. 
Among'  these  is  the  hill  situated  on  the  west  side  of  the  river  just  south  of 
South  Gardiner,  where  the  Maine  Central  Railroad  has  cut  through  about 
30  feet  of  gravel  and  cobbles. 

This  system  shows  a  decided  tendency  below  Waterville  to  follow  the 
crests  or  slopes  of  the  hills  on  one  side  or  other  of  the  river  rather  than  to 
follow  the  bed  of  the  river.  In  general  the  material  is  from  the  size  of  cob- 
bles down  to  sand  grains,  but  here  and  there  the  higher  hillocks  contain 
bowlderets,  and  sometimes  bowlders  2  to  3  feet  in  diameter.  A  pinnacle 
near  the  north  line  of  Augusta  consists,  judging  from  what  can  be  seen  on 
the  surface,  of  a  mass  of  stones  and  bowlders  but  little  water  polished  and 
much  resembling  till. 

Length  of  system,  55  miles. 


LOWER  KENNEBEC  VALLEY  SYSTEM.  173 

Short  eskers  are  reported  by  E.  P.  Clarke  as  occurring  not  far  from 
Sidney  Post-Office.  They  lie  more  than  a  mile  west  of  the  Kennebec 
Valley  system,  and  are  either  local,  or,  perhaps,  branches  of  this  system. 

SHORT    ESKERS    SOUTH    AND    SOUTHWEST    OF    MOOSEHEAD   LAKE. 

Several  short  "horsebacks"  have  been  reported  to  me  as  being  found 
in  the  western  part  of  Shirley,  in  East  Moxie  and  Bald  Mountain  town- 
ships, and  in  the  western  part  of  Blanchard,  near  Bald  Mountain  Pond. 

Near  the  west  end  of  Kingsbury  Pond,  in  Mayfield  and  Brighton,  a 
series  of  several  gravel  ridges  comes  from  the  north  down  a  hill  into  the 
level  ground  near  the  pond.  They  become  reticulated,  and  then  toward 
the  south  the  ridges  become  lower  and  broader  and  finally  coalesce  into  a 
rather  level  delta-plain.  The  ridges  are  hardly  a  mile  long,  and  they  appear 
to  be  simply  a  side-hill  system. 

Another  hillside  esker  is  found  on  the  southern  slope  of  a  hill  which 
lies  on  the  north  side  of  Kingsbury  Pond,  near  the  line  between  Mayfield 
and  Kingsbury,  The  ridge  ends  near  the  base  of  the  hill,  but  does  not 
expand  into  a  delta-plain,  unless  it  be  beneath  the  pond. 

Low  passes  extend  from  Kingsbury  Pond  both  noi'th  and  south,  so 
that  all  the  above-named  gravels  might  possibly  form  a  series  connecting 
either  with  the  Hartland  system  through  Harmony  Village,  or  with  the 
Lower  Kennebec  system  through  the  west  part  of  Harmony  and  Athens, 
or  down  the  Wesserrunsett  Valley  into  Brighton  and  Athens,  or  southwest 
along  the  valley  of  Fall  Brook  toward  Solon.  I  have  not  explored  the 
country  thoroughly.  From  present  information  I  reg'ard  all  the  short 
kames  above  mentioned  as  local,  isolated  eskers,  not  branches  of  a  common 
system.  They  were  a  feature  of  the  last  part  of  the  Grlacial  period,  when 
the  ice  was  retreating  northward. 

LOCAL   ESKERS    IN    RICHMOND    AND    BOWDOINHAM. 

A  short  ridge  of  glacial  gravel  and  cobbles  is  found  in  the  western 
part  of  Richmond  Village.  About  2  miles  west  of  the  village,  near  Abaga- 
dassett  Stream,  are  a  few  short,  rather  flat-topped  ridges  with  no  traceable 
connections.  They  appear  to  be  small  marine  deltas.  A  few  miles  south- 
east of  this  place  is  an  east-and-west  ridge  of  till  on  the  east  side  of  Swan 
Island,  in  the  Kennebec  River.     This  is  probably  a  small  terminal  moraine. 


174  GLACIAL  GEAVELS  OF  MAINE. 

If  so,  these  local  kames  in  Richmond  date  from  about  the  same  period  and 
were  proljably  deposited  by  short  glacial  streams  in  the  sea  at  or  near  the 
front  of  the  retreating  ice.  Another  short  local  kame  is  found  near  the  line 
of  the  Maine  Central  Railroad  about  IJ  miles  south  of  East  Bowdoinham. 

SEDIMENTARY    DRIFT    OF    THE    UPPER    KENNEBEC    VALLEY. 

The  student  of  the  drift  of  Maine  who  begins  at  the  mouth  of  the 
Kennebec  River  and  travels  northward  will  at  once  observe  that  the  lower 
portions  of  the  valley  are  bordered  by  no  such  system  of  terraces  as  those 
of  the  classic  upper  Connecticut  Valley.  There  is  a  low  terrace  of  valley 
drift  near  thp  ^jresent  limit  of  high  water.  Above  that  the  only  terraces  are 
those  eroded  in  the  marine  clay  or  till.  The  marine  clay  near  the  river 
differs  but  little  in  composition  from  that  found  several  miles  awa}^  from  it, 
and  is  thus  proved  to  be  a  rather  deep-water  deposit.  The  clays  cover  the 
valley  to  a  breadth  of  many  miles. 

From  Waterville  northward  there  is  a  change  in  the  character  of  the 
sediments  of  the  valley.  Resting  on  the  till  or  unmodified  glacial  diift  is 
a  thick  sheet  of  sedimentary  clay,  overlain  by  a  stratum  of  coarser  sedi- 
ments. The  latter  composed  the  delta  sands  of  the  river  when  the  sea  stood 
at  230  feet.  Marine  fossils  have  been  found  in  the  lower  clays  as  far  north 
as  Norridgewock.  At  North  Anson  fresh-water  clam  shells  have  been 
found  in  brick  clay  several  feet  below  the  surface.  This  clay  is  apparently 
of  the  same  age  as  the  rest  of  the  underclay  of  the  valley.  But  the  unio 
shells  were  found  near  the  base  of  a  terrace  of  erosion,  so  that  it  is  not  certain 
whether  they  were  deposited  in  the  original  underclay  of  the  valley  or  in 
a  more  recent  erosion  channel.  From  Norridgewock  to  the  coast  the  low- 
est layers  of  the  claj  are  dark  in  color,  often  almost  black,  and  often  with 
the  odor  characteristic  of  the  clam  flat.  Farther  up  the  valley  the  under- 
clay becomes  bluish  gray  in  color  and  is  slightly  coarser,  sometimes  even 
silty.  The  underclay  extends  continuously  up  the  Kennebec  Valley  to  a 
point  2  miles  north  of  Bingham;  also  up  the  larger  tributaries  for  a  consid- 
erable distance  above  their  junctions  with  the  Kennebec.  The  underclay 
partly  covers  the  Anson-Madison  glacial  gravels,  and  near  Solon  overlies 
local  beds  of  well-rounded  cobbles.  It  is  thus  evident  that  glacial  gravels 
were  first  deposited  at  ^^arious  points  in  the  valley,  and  that  these  were  sub- 
sequently covered  by  the  clay.     From  being  near  three-fourths  of  a  mile 


SEDIMENTAEY  DRIFT  OP  UPPER  KENNEBEC  VALLEY.    175 

wide  at  Bingham,  the  clay  broadens  to  2  miles  or  more  in  Solon,  Embden, 
Anson,  and  Madison,  while  below  that  point  the  marine  beds  are  several 
miles  in  breadth.  It  is  not  probable  that  the  clay  covers  the  central  parts 
of  the  valley  north  of  Solon  Village. 

From  Waterville  northward  to  Norridgewock  we  find  overlying  the 
sedimentary  clay  a  stratum  of  sand  rather  horizontally  stratified,  except 
where  it  has  blown  under  the  action  of  the  wind.  In  Fairfield  and  Skow- 
hegan  this  sand  forms  plains  extending  back  from  1  to  3  miles  from  the 
river,  and  it  is  plainly  a  marine  formation,  i.  e.,  the  fluviatile  Kennebec 
delta.  In  places  it  has  been  removed  by  the  wind  or  by  stream,  and  it  is 
difiicult  to  trace  its  original  distribution.  Northward  the  sand  becomes 
coarser  by  degrees  and  in  Madison  passes  into  mixed  sand  and  gravel, 
while  by  the  time  Solon  is  reached  cobbles  and  bowlderets  are  found  more 
than  a  foot  in  diameter  along  the  central  parts  of  the  valley.  From  this 
point  to  within  three  miles  of  the  Forks  well-rounded  pebbles,  cobbles, 
bowlderets,  and  in  places  bowlders  are  found  along  the  central  part  of  the 
valley,  while  at  the  sides  of  the  valley  the  stones  are  not  so  large  and  are 
less  waterworn.  At  the  sides  of  the  valley  this  coarse  stratum  plainly 
overhes  the  underclay.  The  sections  observed  by  me  did  not  show  clay 
beneath  the  gravel  at  the  axis  of  the  valley;  yet  this  may  be  due  to  the 
sliding  down  of  the  overlying  gravel.  Only  at  a  few  places  did  I  find  clay 
in  the  banks  of  the  river  above  Solon,  and  then  it  was  uncertain  whether  it 
was  sediment  of  recent  deposition  or  an  uneroded  portion  of  a  stratum  which 
once  covered  the  valley.  It  thus  appears  that  there  is  little  or  no  clay 
beneath  the  coarse  drift  found  along  the  axis  of  the  valley. 

The  so-called  "horsebacks"  ai-e  among  the  most  interesting  features  of 
the  upper  Kennebec  Valley.  From  Solon  to  Bingham  a  nearly  continuous 
two-sided  ridge  is  found  along  the  west  side  of  the  river,  and  from  that 
point  northward  to  within  3  miles  of  The  Forks  a  similar  ridge  is  found  for 
most  of  the  way  on  the  east  side.  These  ridges  rise  20  to  8U  feet  above 
the  alluvium  at  their  sides.     What  is  the  cause  of  these  ridges? 

Where  they  are  broad  enough  to  have  a  flat  top,  they  have,  by  aneroid, 
substantially  the  same  height  as  the  broadest  of  the  alluvial  terraces  at  the 
sides  of  the  valley,  that  which  constitutes  the  main  sedimentary  plain. 
Where  they  are  narrow,  they  are  usually  lower  than  this  terrace,  and  often 
almost  merge  into  an  uneven  or  hummocky  terrace  many  feet  lower  than 


176  GLACIAL  GRAVELS  OF  MAINE. 

the  j^rincipal  terrace.  The  slopes  of  these  "  horsebacks"  are  about  as  steep 
on  the  side  away  from  the  river  as  the  erosion  chff  which  forms  the  bank 
of  the  river.  The  depression  between  the  central  ridg-es  or  horsebacks  and 
the  alluvial  terraces  at  the  sides  is  of  varying  breadth  up  to  one-eighth 
of  a  mile  or  a  little  more.  This  depression,  being  of  varying  depth  and 
confined  between  the  central  ridge  and  the  lateral  terraces,  presents  a  suc- 
cession of  basins  or  kettleholes.  Some  of  these  are  so  deep  as  to  contain 
lakelets  without  visible  outlets.  Some  of  these  ponds  are  said  to  rise  and 
fall  with  the  water  of  the  river.  One  pond  in  Moscow  is  said  to  be  40  feet 
deep  in  time  of  high  water.  By  aneroid  its  surface  was  several  feet  higher 
than  the- river;  hence  it  must  be  fed  by  springs  from  the  side  of  the  valley 
faster  than  the  water  seeps  through  the  alluvium  into  the  river.  All  this 
favors  the  hypothesis  that  there  is  a  body  of  coarse  alluvium  along  the 
central  part  of  the  valley  rather  easily  permeable  by  water.  In  some 
other  respects  the  interpretation  of  the  facts  is  beset  with  difficulties.  The 
ridges    plainly  have    the   appearance    of  being  uneroded    portions  of  an 


FlQ.  20. — Section  across  Kennebec  Valley,    a,  present  situation  of  river. 

alluvial  plain  which  once  extended  across  the  valley.  It  is  not  so  easy  to 
account  for  the  basins  and  lakelets  in  a  valley  of  erosion.  Here  is  the 
bottom  of  a  so-called  channel  of  erosion  50  to  75  feet  higher  at  one  place 
than  at  another  only  a  short  distance  up  or  down  stream.  Such  ups  and 
downs  are  of  frequent  occurrence  in  the  depression  situated  between  the 
ridges  and  the  terraces  at  the  sides  of  the  valley  away  from  the  river.  If 
this  depression  has  been  cut  down  into  the  alluvial  plain  by  water,  then  we 
must  account  for  the  very  unequal  depth  of  the  channel.  This  question 
Avill  be  referred  to  hereafter.  If  we  assume  that  the  two-sided  ridges  result 
from  the  iinequal  erosion  of  a  once  continuous  alluvial  plain,  why  did  not 
the*  river  continue  enlarging  its  channel  laterally  instead  of  forming-  a  new 
one  on  the  other  side  of  the  valley,  leaving  the  central  portion  of  the  plain 
imeroded?  The  true  answer  to  this  question  probably  is  that  the  alluvium 
of  the  central  part  of  the  valley  is  composed  of  so  much  larger  stones  that 
it  is  less  easily  eroded  than  the  di'ift  at  the  sides.  In  many  places  the 
central  ridge  is  largely  composed  of  cobbles  and  bowlderets,  and  for  some 


SEDIMENTARY  DRIFT  OF  UPPER  KENNEBEC  VALLEY.    177 

disrance  in  the  southern  part  of  Forks  Plantation  it  also  contains  many 
bowlders  2  to  4  feet  in  diameter. 

Is  there  an  ordinary  osar  along  the  axis  of  the  valley,  which  was  sub- 
sequently covered  and  flanked  by  river  drift!  I  regret  that  the  numerous 
sections  examined  by  me  along  the  windings  of  the  river  were  not  free 
from  surface  sliding.  I  could  not  find  an  ordinary  osar  of  arched  strati- 
fication along  the  valley,  but  the  sediments  appeared  to  become  finer 
by  degrees  as  we  go  back  toward  the  sides  of  the  valley,  and  the  coarse 
central  belt  showed  no  distinct  border.  This  kind  of  assortment  is  charac- 
teristic of  the  osar-plain,  and  probably  also  of  fluviatile  drift.  The  stratifi- 
cation of  the  central  ridge  could  not  be  distinctly  made  out,  but  appeared  to 
be  rather  horizontal.  The  pebbles  and  cobbles  are  well  rounded,  far  more 
so  than  in  ordinary  valley  drift  ofi"  from  lines  of  glacial  gravel.  The 
average  slope  of  the  Kennebec  River  from  Moosehead  Lake  to  tide  water 
at  Augusta  is  about  9  feet  per  mile,  and  from  The  Forks  to  Norridgewock 
it  is  probably  not  more  than  4  to  6  feet  per  mile.  Below  Bingham  the 
central  ridges  contain  bowlderets  more  than  a  foot  in  diameter  at  a  point 
where  the  alluvial  plain  is  near  three-fourths  of  a  mile  wide.  Above 
Bingham  the  valley  narrows  to  about  one-fourth  of  a  mile,  here  and  there 
expanding  to  a  half  mile  or  more.  If  the  whole  alluvial  plain  is  ordinary 
river  drift,  a  very  broad  and  swift  river  is  necessary  to  transport  such  large 
stones  and  to  roll  and  round  them  so  thoroughly.  The  question  as  to 
whether  so  moderate  a  slope  could  have  given  the  necessary  velocity  of 
current  will  be  considered  later.  My  exploration  of  this  part  of  the  Kenne- 
bec Valley  was  made  in  1879,  before  I  recognized  the  osar-jjlain.  I 
therefore  somewhat  doubtfully  outline  the  history  of  the  upper  Kennebec 
Valley  as  follows: 

First,  glacial  gravels  were  deposited  in  the  valley  between  The  Forks 
and  Solon  by  glacial  streams  flowing  in  narrow  channels  between  ice  walls. 
These  gravels  are  now  deeply  buried  and  have  been  found  only  here  and 
there.  Subsequently  an  osar-plain  was  formed  along  the  axis  of  the  valley 
in  a  much  broader  ice  channel.  This  channel  gradually  broadened,  until 
at  last  it  extended  across  the  whole  valley,  at  which  time  the  river  ceased 
to  be  a  glacial  stream.  The  gradual  retreat  of  the  ice  from  the  center  of 
the  valley  is  probably  the  explanation  of  the  fact  that  the  alluvial  plain  of 
the  Kennebec  does  not  extend  back  into  several  of  the  lateral  valleys  which 

MON  XXXIV V2 


178  GLACIAL  GRAVELS  OF  MAmE. 

join  the  main  valley  in  this  part  of  its  course.  A  well-marked  instance  is 
found  on  the  west  side  of  the  Kennebec  about  3  miles  north  of  Solon  Vil- 
lage, where  a  valley  covered  by  ordinary  till  comes  from  the  northwest  into 
the  main  valley.  The  Kennebec  alluvial  plain  rises  8  feet  or  more  above 
the  lateral  valley,  and  once  formed  a  dam  across  it,  but  shows  no  tendency 
to  extend  back  into  the  valley.  This  valley  would  have  formed  a  lateral 
bay  of  the  main  river  at  the  time  the  alluvial  plain  was  being  deposited  if 
it  was  not  covered  by  ice.  Near  the  mouth  of  the  Pleasant  River — a  small 
stream  forming  the  outlet  of  Pleasant  Pond,  in  Carratunk — there  is  an  abrupt 
enlargement  of  the  valley  of  the  Kennebec  toward  the  east,  and  the  coarser 
sand  and  gravel  plain  found  near  the  river  does  not  expand  to  fill  the  broad 
valley,  but  is  bordered  by  an  area  of  silt  and  ela}-  on  the  east  side.  This 
clay  extends  for  some  distance  up  the  lateral  valley.  I  see  no  reason  why 
all  the  lateral  valleys  would  not  be  covered  by  such  a  clay  at  least  to  the 
height  of  the  higher  Kennebec  terrace,  if  the  water  were  free  to  flow  back 
into  them  at  the  time  the  terraces  were  being  deposited.  The  fact  that  some 
of  the  lateral  valleys  are  not  covered  by  such  sediments,  though  they  are 
not  so  high  as  the  higher  terraces,  favors  the  hypothesis  that  the  ice  still 
lingered  in  them  after  it  had  disappeared  in  the  main  valley. 

Directly  after  the  melting  of  the  ice  in  the  valley  the  currents  flowed 
gently,  and  the  underclay  was  now  laid  down  in  the  bottom  of  the  valley, 
flanking  the  previously  deposited  osar-plain.  Finally  there  came  a  time  of 
swifter  floods,  when  the  clays  were  covered  by  coarse  sediments  over  the 
whole  of  the  valley  (up  to  3  miles  broad).  Much  of  this  sand  and  gravel 
and  cobbles  was  probably  derived  from  the  central  osar-plain,  which  vms 
now  in  part  eroded  and  spread  laterally  over  the  whole  valley.  At  this 
time  the  river  was  pouring  its  might}^  volume  of  waters  into  the  sea  in 
Anson  and  Madison  or  northward,  while  estuarine  conditions  prevailed  for 
some  miles  above  that  point.  Subsequently  the  sea  retreated  to  its  present 
position,  but  at  this  time  the  Kennebec  had  become  much  reduced  in  vol- 
ume, and  the  change  in  level  must  also  have  been  quite  rapid,  or  a  delta- 
plain  of  sand  would  have  been  left  over  all  the  lower  part  of  the  valley. 
As  it  is,  the  delta  sands  of  the  Kennebec  poured  into  the  sea  can  not  be 
traced  south  of  Waterville.  Below  that  place  the  whole  of  the  broad  area 
occupied  by  the  sea  is  covered  by  clays,  and  these  were  rather  deep-water 
deposits,  formed  some  considerable  distance  from  where  the  Kennebec  River 


ANSON-MADISON  SERIES.  179 

poured  into  the  sea  at  the  time  it  was  depositing'  the  broad  delta  sands  of 
Solon,  Embden,  Anson,  Madison,  Skowhegan,  and  Waterville. 

A  comparison  of  this  valley  with  others  at  the  same  distance  from  the 
coast  strongly  points  to  the  conclusion  that  the  broad  gravel,  sand,  and  clay 
plains  extending  from  Embden  and  Solon  northward  are  frontal  or  overwash 
plains,  dating  from  the  time  when  the  ice  had  retreated  to  a  point  north  of 
Bingham.  These  vast  deposits,  consisting  of  the  underclay  and  the  sur- 
face sands  and  gravels,  were  laid  down  upon  a  series  of  still  older  gravels 
which  were  of  pureh^  glacial  origin  and  have  been  seen  only  in  a  few 
places.  The  glacial  river  probably  flowed  down  the  Kennebec  Valley  to 
Norridgewock  and  then  southward,  not  along  the  river  to  Skowhegan.  A 
low  valley  covered  by  clays  and  silts,  probably  marine,  extends  from  Nor- 
ridgewock southeastward  into  Fairfield,  and  two  other  valleys,  covered  by 
fine  sediments,  extend  southwestward  into  Belgrade.  The  last  named  are 
along  lines  of  glacial  gravels. 

The  glacial,  fluviatile,  estuarine,  and  marine  sediments  are  all  repre- 
sented near  Norridgewock,  and  the  region  is  a  difficult  one  to  understand. 

A  sedimentary  plain  several  miles  broad  covers  the  lower  portion  of 
the  valley  of  the  Sandy  River.  Its  general  character  resembles  that  of 
the  Kennebec  Valley  at  the  same  elevation.  This  alluvial  plain  connects 
southward  by  two  lines  of  clay  with  the  marine  clays.  One  of  these 
lines  of  clay  extends  from  Mercer  Village  southeastward  through  Belgrade 
to  Augusta;  the  other  from  Farmington  Falls  southward  through  Chester- 
ville,  Fayette,  and  East  Livermore  to  Leeds  and  Sebatis.  The  origin 
of  these  sediments  situated  above  the  230-foot  contour  will  be  discussed 
later. 

ANSON-MADISON    SERIES. 

A  dome  of  kame  gravel  76  feet  high  is  found  on  the  south  bank  of 
the  Carrabassett  Stream  about  4  miles  northwest  of  the  village  of  North 
Anson.  Three  other  similar  deposits,  separated  by  gaps  up  to  a  mile  in 
length,  are  arranged  in  a  line  from  this  point  southeastward.  Then  ajjpears 
a  rather  continuous  ridge  which  crosses  a  very  low  divide  and  subse- 
quently follows  the  valle^^  of  Gretchell  Brook  for  several  miles  southeast- 
ward through  Anson.  The  gravels  pass  one-half  mile  west  of  Anson 
Village  (Madison  Bridge),  cross  the  Kennebec  a  short  distance  north  of 
the  mouth  of  Sandy  River,  and  then  appear  as  a  ridge  on  the  east  side 


180  GLACIAL  GRAVELS  OF  MAINE. 

of  the  river  for  about  three-fourths  of  a  mile.  The  southern  portion  of 
this  ridge  is  so  disguised  by  the  sands  and  clays  of  the  valley  that  it 
is  uncertain  whether  it  ends  in  a  delta-plain  or  not. 

The  stones  of  the  series  are  polished,  but  in  general  not  so  much  so 
as  those  of  the  long  systems.  A  noticeable  feature  of  this  series  is  that 
it  is  discontinuous  at  its  northern  extremity  in  the  same  way  that  the  long 
osars  usually  become  discontinuous  at  their  southern  ends. 

The  relation  of  this  system  to  the  osar  border  clay  and  the  alluvium 
of  the  Carrabassett  Valley  is  interesting.  The  gravels  at  the  southern 
extremity  of  the  series  are  more  or  less  covered  by  the  clay  and  sand 
of  the  Kennebec  Valley.  Northward  in  the  valley  of  the  Carrabassett 
the  gravels  are  flanked  by  a  plain  of  nearly  horizontally  stratified  fine 
sediments.  This  bordering  plain  is  of  varying  breadth  up  to  one-fourth 
of  a  mile,  and  extends  all  the  way  to  the  Carrabassett  Stream.  Clay 
and  silty  clay  are  most  abundant  in  the  border  plain,  but  some  layers 
of  sand  alternate  with  the  clay.  The  fact  that  this  plain  follows  the  course 
of  the  glacial  stream  up  and  over  a  divide,  rising  above  the  alluvial  plain  of 
the  Carrabassett  Valley  20  or  more  feet  by  aneroid,  proves  that  the  clay 
along  the  line  of  the  kames  was  not  due  to  an  overflow  of  the  Carra- 
bassett River,  but  was  deposited  in  a  broad  ice  channel.  Here  and  there 
on  the  border  plain  of  clay  are  bowlders  2  to  4  feet  in  diameter.  They 
have  the  shapes  of  the  ordinary  till  bowlders,  and  were  probably  depos- 
ited by  floating  ice.  Near  the  line  of  the  gravels  IJ  miles  south  of 
the  Carrabassett,  wells  30  feet  deep  do  not  reach  the  bottom  of  the 
clay.  At  this  point  is  an  interesting  feature  of  the  osar  border  plain. 
Toward  the  east  it  is  continuous  with  and  fully  as  high  as  the  broad 
plain  of  sand  and  clay  which  extends  about  5  miles  northeastward  across 
the  Carrabassett  River  into  Embdeu.  But  toward  the  west  the  clay 
border  plain  slopes  down  rather  steeply  to  a  swamp,  one-half  mile  or  more 
wide,  which  is  about  20  feet  lower  than  the  plain  itself  A  small  brook 
flows  from  the  swamp  northeastward  across  the  sedimentary  plain  to  the 
Carrabassett,  having  eroded  a  deep  and  narrow  ravine  in  it.  This  small 
stream  can  not  have  eroded  the  clay  over  several  hundred  acres  at  the 
swam]D  and  only  a  narrow  strip  over  the  rest  of  the  alluvial  plain.  On 
the  north  side  of  the  Carrabassett  opposite  this  point  there  is  a  valley 
extending  back  farther  from  the  river  than  this,    yet  it  is   covered  with 


NORRIDGEWOOK-BELGTiADE  SYSTEM.  181 

saud  and  clay  to  the  base  of  the  hig-h  hills.  It  does  not  seem  possible 
the  kame  border  plain  could  end  so  abruptly  as  it  does  on  the  west  at 
the  swamp  above  mentioned,  unless  at  the  time  of  deposition,  of  the  border 
clay  as  well  as  of  the  alluvium  of  the  Carrabassett  Vallej^  at  this  point, 
the  area  where  the  swamp  now  is  was  then  covered  by  ice.  It  is  possible 
that  the  liorder  clay  itself  happened  to  be  just  high  enough  to  prevent  the 
water  of  the  Carrabassett  from  passing  westward,  though  that  condition 
would  be  extraordinary. 

Apparently  the  glacial  history  of  the  region  along  this  gravel  series 
is  as  follows:  A  small  glacial  stream  deposited  the  gravels  in  rather  narrow 
channels  within  the  ice.  By  degrees  this  channel  became  widened  to 
several  times  its  original  breadth,  and  in  this  broad  channel  was  deposited 
the  osar  border  clay.  Then  the  ice  on  the  east  side  of  the  border  clay 
melted  and  the  border  plain  was  submerged  in  the  great  sheet  of  (estu- 
arinel)  water  which  then  filled  the  valley  of  the  Carrabassett  to  a  breadth 
of  several  miles.  But  the  ice  on  the  west  side  of  the  osar  channel,  where 
the  swamp  now  is,  probably  still  lingered  for  a  time  and  prevented  the 
deposition  of  fine  sediments  over  that  part  of  the  valley.  The  swamp 
woiild  naturally  be  covered  by  a  pond  previous  to  the  cutting  of  the 
ravine  of  erosion  to  the  Carrabassett  by  the  small  brook,  its  outlet. 

Some  of  the  short  deposits  of  gravel  at  the  nortli  end  of  the  series  may 
be  small  delta-plains,  and  mark  stages  in  the  extension  of  the  broad  glacial 
channel  northward.  A  possible  connection  of  the  Anson-Madison  series  is 
found  in  Embden.  A  kame  about  three-fourths  of  a  mile  wide  is  found 
between  Fahi  and  Sands  ponds,  in  Embden,  and  another  near  Hancock 
Pond.  I  did  not  explore  the  region  about  Embden  Grreat  Pond,  and  do  not 
know  whether  there  is  a  continuous  series  of  gravels  between  the  two  noted. 
It  is  quite  possible  this  is  a  branch  of  a  Kennebec  Valley  glacial  river. 

Length  of  the  Anson-Madison  series,  about  10  miles. 

NORRIDGEWOCK-BELGRADE    SYSTEM. 

Provisionally  these  gravels  are  classified  as  a  distinct  system,  though  a 
sufficiently  careful  search  beneath  the  sedimentar}^  sand  and  clay  of  the 
Kennebec  Valley  maj^  yet  show  that  they  ai'e  a  continuation  of  the  Anson- 
Madison  system,  and  that  both  are  connected  with  the  gravels  of  the  upper 
Kennebec  Valley. 


182  GLACIAL  GRAVELS  OF  MAINE. 

The  series  begins  near  the  south  line  of  Norridgewock  as  a  number  of 
ridges  separated  by  intervals  varying  up  to  near  1  mile.  The  series  extends 
southwestward  along  a  low  pass  to  Smitlifield  Village,  where  it  expands  into 
a  plain  more  than  50  feet  high.  On  the  north  the  plain  is  continuous  for 
about  one-fourth  of  a  mile  from  east  to  west,  and  it  sends  out  three  parallel 
tongues  south  for  one-third  of  a  mile.  The  material  is  coarse  gravel  and 
cobbles  at  the  north  side  of  the  plain,  but  becomes  rapidly  finer  toward  the 
south,  passing  into  fine  sand,  and  this  into  sedimentary  clay.  A  continuous 
plain  of  sedimentary  clay  extends  from  Norridgewock  along  the  line  of  this 
gravel  series,  and  thence  all  the  way  to  Augusta.  The  surface  of  this  clay 
is  strewn  with  numbers  of  stones  and  angular  bowlders  2  to  12  feet  in 
diameter,  but  not  with  anything  resembling  a  sheet  of  till ;  hence  I  refer 
the  erratic  bowlders  to  floating  ice.  The  bowlders  may  have  been  deposited 
either  in  a  broadened  osar  channel,  in  which  case  this  is  a  plain  of  osar 
border  clay,  or  in  an  arm  of  the  sea,  or  in  an  overflow  channel  of  the  great 
Sandy  River  (Kennebec  estuary  of  that  time).  The  gravel  plain  at  Smith- 
field  Village  is  a  delta-plain  of  some  sort,  and  it  is  situated  at  about  350 
feet  elevation  by  aneroid.  This  makes  it  probable  that  the  glacial  stream 
here  flowed  into  a  glacial  lake,  or,  what  is  equivalent,  a  broadened  osar 
channel.  For  several  miles  south  of  this  point  the  clays  bordering  this 
gravel  series  have  an  elevation  of  more  than  250  feet. 

South  of  Smithfield  Village  there  is  apparently  no  gravel  for  about  2 
miles,  and  then  a  series  of  gravel  ridges  crosses  the  northeastern  arm  of 
Belgrade  Great  Pond.  It  appears  for  about  a  mile  on  the  east  shore  of  the 
pond,  and  at  Horse  Point  runs  southward  into  the  water  as  a  long  gentle 
sloping  cape.  It  reappears  on  the  south  side  of  the  pond,  and  soon  takes 
the  form  of  a  series  of  reticulated  ridges  inclosing  kettleholes  and  lake- 
lets. About  a  mile  north  of  Belgrade  station  of  the  ]\Iaine  Central  Rail- 
road a  rather  level  plain  extends  for  one-fourth  of  a  mile  or  more  to  the  east 
of  the  main  ridge.  It  was  thrown  out  from  the  west  around  the  south  end 
of  the  high  hill  known  as  Belgrade  Ridge.  It  consists  of  rather  horizontally 
stratified  fine  gravel  and  sand,  with  a  few  layers  of  clay,  and  is  plainly  a 
small  delta.  To  the  east  of  this  deposit  hes  the  valley  of  Messalonskee  (Snows) 
Pond,  in  Belgrade  and  Sidney.  The  plain  in  question  is  from  40  to  60  feet 
above  the  pond,  which  is  240  feet  above  the  sea.  East  and  northeast  of  the 
delta-plain  just  described  no  sedimentary  clay  appears  on  the  northwest  side 


NOEEIDGEWOCK-BELGEADE  SYSTEM.  183 

of  Messalonskee  Pond  for  several  miles  toward  Oakland.  If  the  sea  stood 
at  the  level  of  this  delta-plain,  it  would  at  that  time  have  filled  the  valley 
of  Messalonskee  Pond,  and  a  deep  sheet  of  salt  water  4  miles  or  more  wide 
would  have  extended  northward  from  the  northwestern  part  of  Augusta 
through  Belgrade,  Sidnej',  Oakland,  and  Waterville,  and  such  a  body  of 
water  must  have  deposited  abundant  sediments.  The  sudden  disappearance 
of  the  clay  a  short  distance  east  of  the  osar-ridges  north  of  Belgrade  station 
is  inconsistent  with  the  hypothesis  that  the  delta  above  mentioned  was 
deposited  in  the  open  sea.  On  the  contrary,  these  facts  stronglj^  favor  the 
theory  that  the  delta-plains  which  appear  at  intervals  in  the  course  of  the 
system  from  the  south  part  of  Norridgewock  to  Belgrade  station  were 
deposited  in  glacial  lakes,  and  that  the  bordering  plain  of  sedimentary 
clay  is  osar  border  cla}^,  laid  down  in  a  very  broad  channel  within  the  ice, 
or  perhaps  partly  bordered  by  the  hills. 

South  of  this  point  the  gravel  takes  the  form  of  a  continuous  ridge  for 
several  miles,  being  cut  through  by  the  Maine  Central  Railroad  at  Belgrade 
station.  Just  south  of  the  station  the  ridge  is  strewn  with  many  good-sized 
bowlders  having  till  shapes.  In  the  southeastern  part  of  Belgrade  the 
system  expands  into  a  broad  series  of  reticulated  ridges  inclosing  numerous 
kettleholes  and  basins  containing  twenty  lakelets,  most  of  them  without 
visible  outlets.  On  the  west  of  these  plains  the  ridges  have  steep  side 
slopes,  and  are  simply  windrows  of  coarse  gravel,  cobbles,  bowlderets,  and 
bowlders,  all  veiy  well  rounded.  Going  south  and  east  we  find  the  ridges 
becoming  lower  and  broader  and  the  matter  contained  in  them  finer,  and 
they  presently  blend  into  a  rather  level  plain  of  fine  gravel  and  sand  in 
the  northwestern  part  of  Augusta,  and  this  soon  passes  by  degrees  into 
marine  clay  at  an  elevation  of  near  250  feet  or  more. 

A  short  ridge  in  Manchestei'  is  the  only  glacial  gravel  found  south  of 
this  system,  and  that  is  probably  not  connected  with  this.  This  series  dates 
from  the  last  part  of  the  Glacial  period,  when  the  ice  had  retreated  so  far 
northward  that  the  glacial  river  flowed  into  the  sea  in  the  northwest  part  of 
Augusta.  South  of  where  this  glacial  river  flowed  into  the  sea  the  clay  is 
very  deep.  A  stream  has  eroded  it  to  a  depth  of  80  feet,  and  yet  apparently 
has  not  cut  to  the  bottom.  There  is  an  old  sea  beach  on  the  hill  lying  just 
west  of  Augusta,  being  especially  well  developed  on  the  southern  brow  of 
the  hill  near  the  top.     Otherwise  I  have  not  been  able  to  find  any  very 


184  GLACIAL  GEAYELS  OF  MAINE. 

well-developed  beach  in  this  reg-ion.  It  is  therefore  evident  that  the  deep 
sheet  of  clay  northwest  of  Augusta  represents  eroded  till  in  only  a  small 
proportion,  but  was  chiefly  composed  of  the  mud  brought  into  the  sea  by 
the  glacial  river  at  the  delta  of  Augusta  and  Belgrade  above  described. 

NORTH   POND   BKANCH. 

A  north-and-south  ridge  of  glacial  gravel  crosses  North  Pond  in  the 
northeast  part  of  Rome.  It  nearly  divides  the  pond  into  two  parts.  Its 
connections  are  unexplored.  Probably  it  is  a  branch  of  the  Belgrade  sys- 
tem, yet  it  may  nrove  to  be  a  local  deposit. 

MERCER-BELGRADE   BRANCH. 

An  irregular  mound  of  glacial  gravel  80  feet  high  and  one-eiglith  of  a 
mile  in  diameter  is  found  not  far  south  of  ]\Iercer  Village,  at  the  northeast 
base  of  Hampshire  Hill.  A  nearly  north-and-south  valle}'  in  Mercer, 
Rome,  and  Belgrade  extends  for  several  miles  along  the  eastern  base  of 
this  high  hill,  and  in  this  valley  two  streams  take  their  rise,  one  flowing 
north  to  Mercer  Village,  the  other  soutli  and  west  into  Belgrade  Great 
Pond.  A  well-defined  gravel  series  extends  along  this  valley,  now  taking 
the  form  of  terraces  near  the  base  of  the  hill  and  now  appearing  as  a  two- 
sided  ridge  in  the  midst  of  the  valley.  The  ridges  are  10  to  20  feet  in 
height — nowhere  so  high  as  the  large  hummock  at  the  north  end  of  the 
series.  The  series  does  not  expand  into  a  delta-plain  near  Belgrade  Great 
Pond,  into  which  it  runs  from  the  north,  making  it  probable  this  was  a 
ti-ibutary  of  the  Belgrade  system.  At  the  southwest  angle  of  this  pond 
a  short  gravel  ridge,  which  is  in  a  line  with  the  Mercer-Belgrade  series,  is 
found,  about  half  a  mile  west  of  the  main  system,  which  may  be  a  part 
of  the  Mercer  series. 

The  valley  along  this  gravel  series  is  deeply  covered  by  sedimentary 
sand  and  clay,  which  on  the  north. is  continuous  with  the  broad  alluvial 
plain  of  the  Sandy  River  Valley,  and  on  the  south  there  is  a  line  of  similar 
clays  along  the  outlet  of  Belgrade  Great  Pond  all  the  way  in  its  circuitous 
route  to  Messalonskee  Pond,  near  Belgrade  station.  There  seems  to  have 
been  an  overflow  of  the  great  Sandy  River  estuary  this  way,  and  previous 
to  the  melting  of  the  ice  there  may  have  been  some  border  clay  deposited 
along  the  flanks  of  the  gravel  ridges.  This  makes  the  problem  of  the  clays 
of  this  valley  rather  complex. 


UPPER  KEIs^NEBEO  VALLEY.  185 

The  glacial  gravels  iu  Mercer,  Norridgewock,  Smithfield,  Rome,  and 
Belgrade  are  found  in  a  region  diversified  by  numerous  quite  high  hills, 
many  of  them  granite  knobs.  Between  these  hills  are  several  valleys, 
forming  very  low  passes  from  the  valley  of  the  Sandy  River  south  and 
southeast.  The  coiu'ses  of  the  glacial  rivers  were  over  a  gently  rolling 
surface. 

The  length  of  the  series  from  Mercer  to  Belgrade  is  about  10  miles. 

LATE   GLACIAL   HISTORY   OF   THE   UPPER   KENNEBEC   A'ALLEY. 

When  we  compare  all  the  facts  regarding  the  Kennebec  Valley  with 
those  elscAvhere  recorded  regarding  the  neighboring  vallej^s  situated  at 
about  the  same  distance  from  the  sea,  viz,  the  East  Branch  of  the  Penob- 
scot, the  Pleasant.  River,  the  tipper  Piscataquis,  Dexter,  and  Main  streams, 
the  upper  Sebasticook,  Carrabassett,  and  Sandy  River  valleys,  we  seem  to 
have  ground  for  the  following  interpretation  of  the  facts: 

The  earlier  glacial  streams  of  the  upper  Kennebec  Valle}'  left  no  sedi- 
ments (that  I  have  discovered),  or  they  have  been  Ijuried  out  of  sight.  The 
osar  river  that  flowed  from  Norridgewock  southward  dates  from  a  late 
period,  when  the  ice  had  already  melted  so  far  north  that  this  river  flowed 
into  the  sea  in  the  northwestern  part  of  Augusta.  The  northern  tril^utaries 
of  this  river  must  have  drained  the  upper  Kennebec  Valley,  but  it  is  as  yet 
uncertain  whether  they  deposited  any  gravels  during  the  time  in  which  the 
river  continued  to  flow  south  of  Norridgewock.  The  flow  of  this  glacial 
river  south  of  that  place  was  presentlj^  stopped  by  the  retreat  of  the  ice 
and  the  advance  of  the  sea  up  the  Kennebec  Vallej^  to  near  Madison 
Bridge,  north  of  Norridgewock.  The  Anson-Madison  osar  probably  dates 
from  about  the  time  the  sea  advanced  to  Norridgewock.  About  this  time 
the  upper  Kennebec  osar  river  began  to  deposit  gravels  in  that  part  of  its 
channel  lying  north  of  Solon.  Later  the  ice  over  the  bottom  of  the  vallej^ 
had  all  melted  as  far  north  as  Embden  or  Solon.  By  this  time  the  osar 
channel  extending  nearly  from  The  Forks  to  Solon  had  broadened  to  an 
osar-plain  channel,  with  reticulations  and  outliers  in  various  parts  of  the 
valley,  and  the  might}-  glacial  river  that  poured  south  from  Bingham  and 
Solon  formed  a  frontal  plain  of  gravel  and  sand  which  extended  a  few  miles 
southward  and  then  was  continued  to  the  sea  as  a  frontal  plain  of  clay  (the 
uuderclay  of  the  valley  drift  of  this  part  of  the  valley).     The  character  of 


186  GLACIAL  GRAVELS  OF  MAIXE. 

the  sedimentary  drift  of  the  interior  of  tlie  State  thus  evidences  the  pro- 
gressive retreat  of  the  ice,  also  the  probabiHty  that  the  longer  glacial  rivers 
did  not  deposit  sediment  in  all  parts  of  their  long  channels  simultaneously. 

SHORT   ESKERS   IN   MANCHESTER   AND   LITCHFIELD. 

The  following  gravel  deposits  do  not  seem  to  have  connections,  and 
are  probably  so  many  local  kames. 

A  small  ridge  is  found  a  short  distance  east  of  The  Forks,  Man- 
chester. A  similar  ridge  is  found  in  the  east  part  of  Bowdoin,  and  still 
another  a  short  distance  east  of  Litchfield  Post-Ofifice ;  and  there  are  several 
ridges  forming  almost  a  series  in  the  valley  of  the  Cobbosseecontee  Stream 
in  Litchfield.  All  these  are  well  disguised  by  the  marine  clays.  Litchfield 
Plains  are  a  small  marine  delta,  without  traceable  connections.  This  plain 
will  be  more  fully  described  later. 

LITCHFIELD-BOWDOIN  SYSTEM. 

Purgatory  Stream  rises  in  the  southwestern  part  of  Litchfield  and 
flows  northeast  into  the  Cobbosseecontee  Stream.  About  a  mile  north  of 
the  soiith  line  of  Litchfield  an  osar-plain  begins  in  the  valley  of  Purgatory 
Stream  and  goes  southward  up  this  valley  to  its  end.  The  gravel  system 
then  crosses  a  hill  about  100  feet  above  its  north  end,  being  somewhat 
interrupted  near  the  top  of  the  divide,  and  then  continues  southward  through 
Webster  into  Bowdoin.  Not  far  north  of  West  Bowdoin  the  series  expands 
into  a  plain  2  miles  or  more  long,  the  gravel  becoming  finer  toward  the 
south  and  quite  level  on  the  top,  passing  from  sand  into  marine  clay.  It  is 
somewhat  fan-shaped,  and  was  a  delta  deposited  in  the  open  sea.  At  the  first 
settlement  of  the  country  it  was  overgrown  by  huge  pines  and  was  called 
the  "Pine  Nurser)^"  Many  masts  of  ships  were  procured  here.  South  of 
this  point  the  system  becomes  very  discontinuous,  and  consists  of  several 
lenticular  ridges  or  domes,  separated  by  rather  short  gaps.  A  mound  of 
this  series  situated  just  east  of  West  Bowdoin  incloses  a  deep  kettlehole. 
Its  flanks  are  partly  covered  by  blowing  marine  sand,  and  it  is  sprinkled 
with  some  large  bowlders  having  the  shape  of  till  bowlders. 

This  is  a  short  series,  but  contains  a  large  amount  of  gravel  and  sand 
for  its  lengtli.  The  stones  are  fairly  well  rounded.  The  breadth  of  the 
gravel  plain  at  the  north  end  of  the  system  is  one-eighth  mile  or  more,  a 


.1      TUNNEL    IN    DOME-LIKE   GRAVEL    MASSIVE:    WEST   BOWDOIN 


11      RAVINES    IN    GRAVEL    PARALLEL    IN    DIRECTION    TO   THE   GLACIAL   RIVER:    DURHAM 


DEAD  RIVER-JEEUSALEM  SYSTEM.  187 

greater  breadth  tlian  usual  iu  such  a  situation.  The  valley  of  Purgatory 
Stream  to  the  northeast  is  from  one-third  of  a  mile  to  more  than  a  mile  in 
breadth.  The  appearances  are  as  if  the  valley  was  occupied  by  a  local 
tongue  of  ice  which  continued  its  motion  while  the  gravel  plain  Avas  being 
deposited.  If  so,  the  space  between  the  front  of  the  ice  and  the  hill  to  the 
south  would  be  occupied  by  a  broad  glacial  stream,  or  by  a  lake,  and  the 
osar-plain  may  in  part  partake  of  the  nature  of  a  water-washed  terminal 
moraine. 

The  system  evidently  dates  from  a  late  period  of  the  Ice  age,  since 
the  marine  delta  near  its  southern  extremity  is  situated  so  far  from  the 
present  coast. 

LOCAL   BSKEES   IN   NORTHWESTERN   MAINE. 

Horseback  at  Leadbetter  Falls. — Tliose  falls  are  situatcd  ou  the  Pcuobscot  River 
near  its  source.  Prof  C.  H.  Hitchcock  describes  a  ridge,  presumably  of 
glacial  gravel,  as  foliows:  "At  the  farther  end  of  the  portage  is  a  large 
horseback,  which  terminates  here  in  a  ledge  larger  than  the  ridge  itself 
We  traced  this  horseback  up  the  river  for  3  miles,  and  found  it  was  not 
parallel  with  the  river  itself"^ 

Pariin  Pond  horsebacks. — Profcssor  Hitclicock  also  describcs  a  horseback  near 
Parlin  Pond,  as  follows:  "Northwest  from  Pariin  Pond  there  is  a  curving 
horseback  three-fourths  of  a  mile  long."^  I  am  informed  that  there  is 
another  similar  ridge  northeast  of  the  pond,  near  its  outlet. 

Kibby  Stream  horseback. — A  two-slded  ridge,  probably  of  glacial  gravel,  is 
reported  by  Mr.  A.  J.  Lane,  of  Lexington,  and  others  as  being  found 
between  Spectacle  Pond  and  Kibby  Stream,  which  flows  into  Dead  River 
at  Grand  Falls. 

DEAD    RIVER-JERUSALEM    SYSTEM. 

From  the  great  bend  of  the  Dead  River  in  Dead  River  Plantation,  a 
very  low  valley  extends  soiithward  past  the  east  base  of  Mount  Bigelow. 
Bog  Brook  takes  its  rise  near  the  highest  part  of  this  pass  and  flows  slug- 
gishly northward  to  the  Dead  River.  A  ridge  of  sand  and  gravel  begins  a 
short  distance  south  of  Dead  River  and  follows  the  valley  of  Bog  Brook. 
It  forms  a  natural  roadway  through  a  low  level  region  near  the  axis  of  the 

'  Second  Annual  Report  upon  the  Natural  History  and  Geology  of  the  State  of  Maine,  p.  345, 1862. 
^Ibid.,  p.  3<I9. 


188  GLACIAL  GRAVELS  OF  MAINE. 

valley.  According  to  the  information  which  has  reached  me,  there  are  two 
low  passes  from  the  head  of  Bog  Brook,  one  southward  along  a  branch  of 
Sevenmile  Stream  to  Kingfield,  the  other  southeastward  through  Lexington 
to  New  Portland.  A  large  plain  of  sand  and  gravel  is  found  in  the  ^'alley  of 
Sevenmile  Stream  above  Kingfield;  also  in  the  Carrabassett  Valley  above 
North  New  Portland.  These  sediments  extend  across  the  valle}'s  in  the 
position  proper  to  valley  drift.  The  gravel  may  have  been  brought  down 
from  the  Dead  RiA'er  region  b}^  glacial  streams  at  a  time  when  the  ice  still 
remained  in  the  valley  of  Dead  River,  but  had  melted  over  the  valleys  to 
the  south.  It  is  quite  possible  also  that  some  of  the  alluvium  of  these  val- 
leys is  after  the  order  of  the  osar-plain.  My  exploration  of  these  valleys 
did  not  reach  above  Kingfield  and  North  New  Portland. 

stratton  Brook  horseback. — A  two-sidcd  ndgc  Is  rcportcd  by  Rev.  Stephen 
Allen,  of  Winthrop,  as  being  situated  between  Stratton  Brook  and  the  road 
from  Eustis  to  Kingfield.  It  is  said  to  begin  4  miles  from  Eustis  and  to 
extend  3  miles  southeastward. 

A  horseback  3  miles  long  is  reported  as  being  found  near  the  divide 
between  Arnold  River,  a  tributary  of  the  Chaudiere,  and  the  Dead  River, 
above  Chain  Lakes. 

NOTE  ON  THE  NORTHWESTERN  PART  OF  MAINE. 

West  of  the  Kennebec  River  and  north  of  a  line  di-awn  from  the 
upper  Androscoggin  Lakes  to  Anson,  the  glacial  gravels  appear  to  be 
scanty  as  compared  with  those  of  the  area  south  of  that  line.  But  the 
same  can  be  said  of  the  whole  of  the  State  northeastward  at  the  same 
distance  back  from  the  coast.  The  distinct  ridges  are  short,  and  several  of 
them  are  lost  in  a  sedimentary  plain  that  presents  the  external  features  of 
a  frontal  plain  of  glacial  sediments.  The  relations  of  the  osars  to  the 
frontal  plains  of  apparent  valley  drift,  and  of  these  to  the  silty  and  clayey 
plains  which  reach  all  the  way  down  to  the  old  sea-level,  furnish  an  intri- 
cate problem.  The  matter  will  be  discussed  more  fully  hereafter.  A  com- 
parison of  the  alluvium  of  the  valle^^s  of  the  streams  situated  in  the 
interior  of  the  State,  from  the  Sandy  River  to  the  East  Branch  of  the 
Penobscot,  reveals  manj^  features  common  to  all  of  these  valleys.  Perhaps 
no  one  of  them  would  alone  warrant  the  belief  that  these  plains  of  sand, 
gravel,  silt,  and  clay  which  reach  from  the  extremities  of  the  short  osars 


EEADFIELD-BRUNSWIOK  SYSTEM.  189 

are  frontal  plains  of  glacial  sediments,  but  all  together  make  out  a  strong 
case.  Every  time  I  review  the  subject  I  am  more  impressed  with  the  weight 
of  this  cunuilative  evidence. 

All  the  facts  so  far  as  known  indicate  that  the  short  eskers  and  osars 
of  noi'thwestern  Maine  are  a  feature  of  the  very  last  part  of  the  glacial 
epoch,  when  the  ice  had  retreated  as  far  north  as  this  region,  and  the 
glacial  rivers  were  consequently  rather  short. 

READFIELD-BRUNSWICK    SYSTEM. 

This  interesting  system  begins  2  miles  northeast  of  Readfield  Village 
as  a  low  ridge  of  rather  fine  subangular  gravel,  which  extends  about  1  mile 
south  to  Lake  Maranocook.  No  glacial  gravel  is  known  to  appear  on  the 
shore  of  this  lake  until  we  reach  Winthrop  Village.  The  eastern  part  of  the 
barrier  which  separates  the  upper  and  lower  Winthrop  lakes  is  underlain  by 
rock  at  a  depth  of  a  few  feet.  Along  the  line  of  the  Maine  Central  Rail- 
road, in  the  western  part  of  the  village,  is  a  north-and-south  valley  extend- 
ing from  one  lake  to  the  other.  The  surface  of  this  valley  rises  about  20 
or  25  feet  above  the  upper  pond,  and  wells  show  it  to  be  covered  by  glacial 
sand  and  gravel,  flanked  by  sedimentary  clay,  to  a  depth  of  more  than  40 
feet.  Evidently  the  preglacial  drainage  flowed  along  this  valley,  and  the 
barrier  of  sand,  gravel,  and  clay  which  now  separates  the  ponds  dates  from 
glacial  time,  or  in  part  was  contemporaneous  with  the  sea.  In  several 
places  in  "Winthrop  Village  and  the  vicinity  marine  fossils  have  been  found 
at  an  elevation  of  200  to  214  feet.  Probably  the  plain  which  separates  the 
upper  and  lower  ponds  was  a  delta-plain,  deposited  in  the  sea  by  a  small 
glacial  stream  from  Readfield. 

About  three-fourths  of  a  mile  south  of  Winthrop  Village,  on  the  west 
shore  of  the  lower  pond  (Lake  Anabescook),  is  a  short  ridge  of  gravel  and 
well-rounded  cobbles,  which  at  one  place  rises  into  a  cone  or  mound  30 
feet  high.  This  ridge  has  been  extensively  excavated  by  the  railroad  com- 
pany. Then  there  is  an  apparent  gap  in  the  system  till  we  reach  the 
south  end  of  the  lake.  Here  a  short  distance  north  of  East  Monmouth,  on 
top  of  hills  rising  50  to  100  feet  above  the  lake,  is  a  capping  of  glacial  gravel 
one-third  mile  long  from  north  to  south  and  not  quite  so  broad.  The  gravel 
is  a  rather  round-topped  plain,  divided  along  the  center  by  a  narrow  north- 
and-south  ravine,  which  does  not  reach  to  the  bottom  of  the  gravel.     No 


190  GLACIAL  GRAYELS  OF  MAINE. 

water  sli®wed  in  this  ravine  at  the  time  of  my  exploration.  The  hill  slopes 
outward  in  all  directions,  and  it  does  not  seem  possible  there  conld  be  so 
large  an  amount  of  erosion  in  such  a  position  by  either  surface  waters, 
boiling  springs,  or  frost  damming.  The  ravine  is  in  places  10  feet  deep, 
and  on  the  lower  slopes  of  the  hill  no  gravel  could  be  found  that  appeared 
to  have  come  from  this  ravine.  There  is  therefore  no  proof  that  the  shape 
of  the  deposit  has  been  materially  changed  since  its  original  deposition. 

South  of  this  gravel  plain  in  Monmouth  is  a  rather  level  country  show- 
ing only  very  low  hills.  At  intervals  of  about  a  half  mile  there  are  two 
other  slightly  round-topped  deposits  of  nearly  the  same  size  as  that  near 
the  lake.  Both  of  them  are  also  divided  into  nearly  equal  parts  by  north- 
and-south  ravines.  Seen  from  the  high  hills  of  southern  Monmouth,  these 
three  ravines  appear  to  be  arranged  in  a  nearly  straight  line.  In  neither 
case  is  there  any  pointed  hill  or  rock  in  a  line  with  these  ra'sdnes,  and  there 
is  lao  feature  of  the  ground  surface  which  accounts  for  them.  The  gravel 
and  cobbles  of  all  three  of  these  plains  are  well  rounded,  and  they  all 
contain  coarser  matter  foward  the  northern  and  central  parts  of  the  plains. 
They  all  are  imperfect  deltas  of  some  sort.  The  more  northern  plain  is 
situated  at  an  elevation  of  about  275  feet,  and  the  gravel  plainly  does  not 
pass  by  degrees  into  the  marine  clays.  It  must  have  been  formed  where 
the  glacial  stream  was  only  partially  checked,  since  it  contains  fine  gravel 
and  coarse  sand  to  the  edge,  where  it  ends  abruptly.  This  indicates  that 
a  glacial  river  here  flowed  into  a  broad  pool  within  the  ice.  The  two  more 
southern  of  these  plains  are  situated  in  the  midst  of  the  marine  clay,  yet 
the  transition  from  the  plain  of  sand  to  the  clay  is  very  rapid.  The  current 
here  was  more  fully  stopped  than  at  the  northern  plain.  It  is  uncertain 
whether  these  latter  are  marine  deltas  or  deltas  of  glacial  lakes.  Even  if 
the  glacial  river  here  flowed  into  the  sea,  it  seems  to  have  been  confined 
between  ice  walls  at  the  sides.  The  ravines,  on  this  theory,  were  formed 
in  front  of  where  the  glacial  torrent  shot  into  the  stiller  water,  the  gravel 
which  was  carried  along  by  it,  so  long  as  it  was  confined  within  a  narrow 
ice  channel,  being  thrown  out  at  each  side  as  it  entered  the  broader  water- 
way.    The  ravines  are  the  channels  of  the  rivers. 

No  gravel  is  found  for  about  one-third  of  a  mile  as  we  continue  to  go 
southward,  and  then  we  come  to  a  very  large  mass,  on  which  a  cemetery 
is  situated.     In  addition  to  sand  and  gravel,  it  contains  great  numbers  of 


READFIELD-BEUNSWICK  SYSTEM.  191 

well-rounded  col3bles,  bowlderets,  and  bowlders  up  to  2  feet  in  diameter. 
This  gravel  deposit  is  very  irregular  in  outline,  and  it  sends  out  several 
spurs  both  north  and  south.  The  surface  is  very  uneven,  showing  a  great 
variety  of  mounds,  ridges,  terraces,  and  shallow  kettleholes.  Most  of  the 
ridges  trend  north  and  south.  It  rises  40  to  80  feet  above  the  plain  of 
sedimentar}^  (probably  marine)  clay  which  partly  covers  its  base.  It  is 
about  three-fourths  of  a  mile  long  from  east  to  west,  and  the  longest  spurs 
are  about  a  half  mile  from  north  to  south.  These  dimensions  show  that  it 
contains  a  very  large  amount  of  glacial  gravel.  The  formation  is  much 
finer  in  composition  in  some  parts  than  in  others,  but  these  parts  are  inter- 
spersed irregularly  among  the  areas  containing  coarser  matter,  so  that  it 
must  be  considered  a  conopound  delta  or  plexus  of  broad  reticulated  ridges, 
composed  of  a  number  of  more  or  less  distinct  but  adjacent  deltas,  rather 
than  a  single  delta.  So  far  as  I  could  discover,  none  of  these  incomplete 
deltas  pass  into  marine  clays  by  degrees,  and  the  glacial  streams  flowed  into 
pools  within  the  ice  rather  than  into  the  open  sea. 

A  broad  low  valley  extends  from  the  foot  of  Sabatis  Lake,  in  Webster, 
northeastward  through  Wales  and  Monmouth,  broadening  as  it  approaches 
Cobbosseecontee  Great  Pond  and  Lake  Anabescook.  This  plain  is  all  the 
way  covered  by  clay,  which  in  several  places  contains  marine  fossils. 
It  is  thus  proved  that  there  was  once  a  continuous  body  of  salt  water 
extending  from  the  Kennebec  Bay  westward  to  Winthrop,  and  thence 
southwestward  to  Sabatis  and  Lisbon,  where  it  broadened  into  the  Andros- 
coggin Bay  of  that  period,  which  covered  a  large  part  of  Topsham, 
Brunswick,  Lisbon,  and  Durham. 

South  of  the  plain  at  the  cemetery  in  Monmouth  there  is  a  gap  of 
about  3  miles,  where  no  glacial  gravel  was  seen  rising  above  the  marine 
clay.  Then  a  series  of  low  bars  separated  by  short  intervals  begins  not 
far  north  of  East  Wales  and  extends  south  along  the  eastern  base  of  the 
high  hills  known  as  Monmouth  Ridge  and  Sabatis  Mountain.  These  gravel 
deposits  lie  in  the  midst  of  the  clay-covered  plain  before  described,  and  are 
partly  covered  by  the  clay.  Near  the  south  base  of  Sabatis  Mountain  the 
series  expands  into  a  very  high  broad  ridge,  becoming  broader  toward 
the  southwest  and  of  finer  material,  ending  in  sand,  which  is  overlain  at  the 
base  by  the  marine  clay.  Here  the  glacial  streams  flowed  into  a  glacial 
lake  or  into  the  sea,  but  if  the  latter,  the  transition  from  the  sand  to  the 


192  GLACIAL  GRAVELS  OF  MAINE. 

clay  is  so  abrupt  as  to  indicate  that  the  glacial  waters  were  quite  suddenly 
checked  after  entering  the  salt  water.  This  delta  is  situated  near  the  south- 
east angle  of  Sabatis  Pond.  Going  south  we  find  no  glacial  gravel  rising 
above  the  marine  clays  for  somewhat  more  than  2  miles.  Then  a  low  plain 
about  half  a  mile  long  is  found  on  the  west  side  of  Sabatis  Stream,  and 
then  there  is  another  gap  of  half  a  mile.  A  nearly  continuous,  low,  broad 
ridge  then  begins  and  extends  southward  to  Lisbon  station  of  the  Maine 
Central  Railroad.  Just  north  of  the  station  it  expands  into  a  broad  ridge 
or  mound  called  Whites  Hill,  which  rises  fully  100  feet  above  the  clay 
covering  its  base.  Wells  show  this  clay  to  be  more  than  40  feet  deep. 
From  this  place  southeastward  to  Lisbon  Falls  extends  what  is  known  as 
Lisbon  Plain.  It  is  a  rather  level  plain  of  horizontally  stratified  sand  and 
clay,  while  here  and  there  low  ridges  of  glacial  gravel  rise  above  the  finer 
sediments  which  overlie  it.  This  plain  lies  in  the  angle  between  Sabatis 
Stream  and  the  Androscoggin  River,  and  at  the  time  the  sea  was  expanded 
would  be  subject  to  the  action  of  the  tidal  cm-rents  of  both  the  valleys. 
On  general  grounds  this  plain  might  be  considered  a  marine  delta,  brought 
down  from  the  north  by  the  glacial  river  we  have  been  tracing,  but  its  prox- 
imity to  the  Androscoggin  makes  it  certain  that  it  is  in  part  an  Androscog- 
gin River  delta.  East  of  Lisbon  Falls  this  gravel  series  consists  of  four 
broad  ridges  or  plains,  all  sitiiated  on  the  north  bank  of  the  Androscoggin 
River.  The  first  is  situated  about  one-fourth  of  a  mile  east  of  Lisbon 
Falls.  The  second  is  about  1^  miles  east  of  this,  and  consists  of  two  large 
and  broad  ridges,  inclosing  a  deep  kettlehole.  The  kame  stuff  is  here  very 
coarse,  containing  great  numbers  of  very  round  cobbles,  bowlderets,  and 
bowlders.  This  deposit  is  half  a  mile  long  from  east  to  west,  and  about 
half  as  broad,  and  rises  100  feet  above  the  Andi-oscoggin  River.  About  1 J 
miles  farther  east  is  another  mass  of  glacial  gravel  of  about  the  same  size 
as  the  last  named,  but  rather  level  on  the  top  and  containing  few  large 
stones.  At  the  river  bank  it  forms  a  steep  blutf  100  feet  high.  After 
another  interval  of  about  1^  miles  a  fourth  plain  of  sand,  gravel,  and  cob- 
bles is  found  as  a  terrace  rising  only  30  or  40  feet  above  the  Andi-oscoggin 
River.  It  is  not  more  than  one-fourth  of  a  mile  long  and  less  than  half  as 
broad.  Its  situation  near  the  river  and  its  level  top  make  it  resemble  val- 
ley drift,  from  which  it  can  readily  be  distinguished  by  a  comparison  with 
the  drift  of  the  river  above  and  below  this  point.     The  stones  of  this  gravel 


WAYNE-MONMOUTH  BRANCH.  193 

terrace  are  much  rounder  than  those  of  the  Audi'oscoggin  flood  plain  or 
those  in  the  bed  of  the  river,  and  no  continuous  sheet  of  such  drift  is  found 
along  the  river.  This  plain  is  situated  2  J  miles  west  of  Brunswick  Village, 
and  I  have  been  able  to  find  no  similar  gravels  east  or  southeast  of  it.  I 
therefore  assume  this  to  be  the  end. 

In  a  few  places  this  system  is  situated  above  the  contour  of  230  feet, 
as,  for  instance,  in  Readfield  and  near  East  Monmouth.  In  several  places 
the  tops  of  the  ridges  rise  above  that  contour,  though  their  bases  are  below 
it.  This  system  is  discontinuous  from  one  end  to  the  other,  and  by  this  it . 
is  meant  that  the  gi'avels  were  originally  so  deposited.  The  forms  of  the 
gravel  masses  vary  miich  and  the  system  can  hardly  be  classified  among- 
the  discontinuous  systems  of  lenticular  masses.  The  deposits  of  this  sys- 
tem are  more  hummocky  and  irregular  in  shape.  Nearly  all  of  the  plains 
show  some  of  the  characteristics  of  the  delta,  but  not  such  deltas  as  would 
be  formed  in  the  open  sea,  unless  the  plain  near  the  foot  of  Sabatis  Pond 
be  such  a  one. 

The  length  of  the  system  is  25  miles. 

AVAYNE-MONMOUTH   BRANCH. 

This  series  begins  a  little  more  than  2  miles  east  of  "Wayne  Village. 
At  the  north  end  it  is  a  small,  rather  straight  ridge.  The  stones  here  pre- 
serve their  till  shapes,  and  the  mass  is  quite  like  till  in  appearance,  having 
a  rather  pellmell  structiire;  yet  close  examination  shows  that  the  finest 
detritus  has  been  washed  out  of  the  mass  and  the  stones  are  a  little  water- 
worn.  Farther  south  the  ridge  becomes  very  crooked  and  meandering  and 
the  stones  are  much  more  worn  and  rounded.  There  are  mau}^  water- 
polished  bowlders  in  the  ridge.  Within  less  than  a  mile  the  system  becomes 
double,  consisting  of  a  continuous  low  ridge  in  a  valley  and  a  parallel  dis- 
continuous series  of  domes  or  short  plains  forming  low  broad  caps  to  a 
series  of  hillocks  lying  along  the  west  side  of  the  valley.  Just  south  of 
Evergreen  Cemetery  there  is  a  short  gap  in  the  series,  and  then  another 
gravel  cap  on  top  of  a  low  rock  ridge,  which  ends  near  a  small  stream  that 
flows  southwest  into  Wilson  Pond.  No  glacial  gravel  appeared  along  this 
stream  or  pond.  Right  in  front  of  the  last-named  gravel  deposit  is  the 
southwestern  spur  of  Mount  Pisgah,  a  high  hill  situated  in  southwestern 
Wiutlu-op  and  northern  Monmouth.  Over  this  hill  the  road  is  made  which 
MON  xxxiv 13 


194  GLACIAL  GEAVELS  OF  MAINE. 

leads  from  Wajnie  to  North  Monmouth,  and  it  rises  150  feet  while  crossing 
the  spm-  of  the  hill.  Parallel  with  the  road  is  a  U-shaped  ravine  from  20 
to  40  feet  deep  on  the  steeper  slopes  of  the  hill,  but  hardly  perceptible  for 
a  short  distance  near  its  top.  The  ravine  is  found  on  both  the  north  and 
south  slopes.  Till  shows  in  the  bottom  of  the  ravine,  and  it  is  strewn  with 
many  more  bowlders — 2  to  4  feet  in  diameter — than  appear  in  the  fields  of 
till  at  each  side.  This  fact  indicates  that  this  is  a  ra^dne  of  erosion.  The 
bottom  of  the  ra^dne  is  rather  level  in  cross  section  and  is  from  30  to  100 
feet  wide.  This  is  an  extraordinary  amount  of  erosion  in  the  till.  But  the 
drainage  slopes  are  only  about  a  half  mile  long  on  each  side  of  the  hill,  no 
springs  or  streams  appeared  in  the  valley  at  the  time  of  my  examination, 
and  the  bottom  was  wholly  grassed  over,  except  a  small  channel  on  the 
southeastern  slope  eroded  by  the  rains.  Assuming  that  this  canal-like 
depression  with  rather  steep  banks  is  the  result  of  erosion,  the  rains  and 
shower  streams  do  not  seem  competent  for  the  work,  judging  from  the 
amount  of  erosion  accomphshed  by  the  streams  of  this  part  of  the  State. 

Passing  a  short  distance  down  the  southeastern  slope,  we  come  to  a 
rido-e  of  well-rounded  glacial  gravel  which  extends  through  the  village  of 
North  Monmouth  and  then  becomes  discontinuous.  Two  or  three  small 
plains  of  gravel  take  us  to  the  plain  at  the  cemetery  southeast  of  Mon- 
mouth, already  described.  Here  this  tributary  probably  joined  the  main 
river,  and  one  or  more  of  the  northern  spurs  of  that  irregular  plain  may 
have  been  deposited  by  it. 

It  is  thus  proved  that  a  glacial  river  flowed  from  the  north  to  the  base 
of  the  southwestern  spur  of  Mount  Pisgah.  The  only  trace  of  any  con- 
nection is  found  on  the  southeastern  side  of  this  hill.  It  is  thus  made 
highly  probable  that  a  glacial  river  flowed  up  and  over  this  hill,  150  feet 
hio-h,  along  the  line  of  that  remarkable  ravine.  The  great  erosion,  which 
could  not  be  accounted  for  by  the  action  of  the  rains,  thus  becomes  intelh- 
gible.  A  glacial  stream  here  eroded  a  large  body  of  till,  probably  in  con- 
siderable measure  a  part  of  the  ground  moraine.  Why  did  it  not  erode 
the  till  at  the  top  of  the  hill  equally  with  that  farther  down  its  slope! 

The  large  size  of  the  bowlders  near  the  north  end  of  the  series  favors  the 
hypothesis  that  this  was  a  subglacial  stream.  There  are  some  remarkable 
heaps  of  till  on  the  southern  slopes  of  Mount  Pisgah  that  deserve  study. 

The  length  of  the  branch  is  7  miles. 


EEADPIELDBRUISTSWICK  SYSTEM.  195 

G-RATELS   NEAR    SABATIS   POND. 

About  IJ  miles  northwest  of  Sabatisville  and  a  sliort  distance  Avest  of 
Sabatis  Pond  is  a  ridge  of  gravel,  coljbles,  and  bowlderets,  having  an 
arched  cross-section.  It  is  hardly  an  eighth  of  a  mile  in  length,  and 
appears  to  have  no  connections  except  a  dejDOsit  on  a  hillock  a  few  rods  to 
the  south.  The  gravel  cap  on  this  hillock  is  only  50  feet  in  diameter. 
Excavations  near  the  road  show  that  4  to  6  feet  of  gravel  covers  the  top  of 
a  hillock  of  till.  The  gravel  is  distinctly  but  not  very  much  polished  and 
rounded. 

The  plain  at  the  southeast  corner  of  Sabatis  Lake  has  already  been 
referred  to.  The  main  part  of  this  plain  was  deposited  by  the  glacial 
river  which  flowed  from  the  direction  of  East  Wales  and  Monmouth,  but  a 
spur  extends  for  one-eighth  of  a  mile  or  more  northwest  along  the  lake 
toward  Leeds.  The  Maine  Central  Railroad  cuts  through  this  ridge,  but  I 
could  find  no  recent  excavations  showing  the  lines  of  stratification.  There 
is  therefore  no  direct  evidence  as  to  the  direction  of  the  glacial  stream 
which  deposited  it,  except  the  fact  that  the  material  is  coarser  on  the  north 
than  farther  south.  This  negatives  the  theory  that  it  was  thrown  out 
westward  around  the  southern  base  of  Sabatis  Mountain  by  the  eastern 
glacial  river  (that  from  Monmouth  and  Wales).  The  proof  is  reasonably 
strong  that  it  was  deposited  by  a  stream  from  the  northwest,  i.  e.,  the 
direction  of  Leeds.  About  a  mile  southwest  of  this  point  a  small  terminal 
moraine  is  found  in  the  southern  part  of  the  village  of  Sabatisville.  The 
moraine  is  but  little  water  washed  and  its  base  is  overlain  by  the  marine 
clay.  It  was  probably  formed  at  the  foot  of  the  ice  where  it  confronted 
the  sea.  All  the  facts  agree  in  proving  the  presence  of  the  sea  as  far  north 
as  the  foot  of  Sabatis  Pond. 

MOUNT    VERNON   ESKER. 

This  is  a  small  hillside  system  less  than  one-fourth  of  a  mile  in  length. 
It  is  found  a  short  distance  east  of  Mount  Vernon  Village.  It  begins  near 
the  southern  brow  of  a  rather  flattish-topped  hill,  and  at  the  base  of  the  hill 
it  ends  in  a  small  enlargement  ajDpearing  to  be  a  diminutive  delta-plain, 
which  incloses  a  depression  (kettlehole!)  occupied  by  a  small  peat  swamp. 
It  is  a  small  deposit,  but  a  fair  type  of  the  sidehill  eskers. 


196  GLACIAL  GRAVELS  OF  MAINE. 


CHESTERVILLE-LEEDS   SYSTEM. 


This  important  system  appears  to  begin  about  1^  miles  north  of  Ches- 
terville  Village  as  an  osar-plain  or  terrace,  which  soon  becomes  a  narrower 
ridge.  It  passes  a  little  to  the  east  of  Chesterville  Village,  and  thence  takes 
a  nearly  straight  course  southward  to  the  Twelve  Corners  in  Fayette.  For 
several  miles  south  of  Chesterville  Mills  it  takes  the  form  of  a  high,  broad 
ridge,  with  outlying  plains  and  ridges  inclosing  kettleholes  and  some  small 
lakes.  It  is  here  called  Chesterville  Ridge,  and  as  it  rises  50  or  more  feet 
above  a  very  level  plain,  it  forms  a  remarkable  feature  of  the  landscape. 
In  the  southern  part  of  Chesterville  the  main  ridge  becomes  lower  and 
broader,  and  passes  into  an  osar-plain,  which  continues  south  tln-ough  a 
very  low  pass  at  Twelve  Corners  and  thence  past  the  Camp  Grround  in 
East  Livermore.  Then  there  appears  to  be  a  short  gap  in  the  system,  but 
it  soon  begins  again  as  a  two-sided  ridge  of  arched  stratification.  This  low 
and  broad  osar  crosses  to  the  west  of  the  Maine  Central  Railroad  not  far 
north  of  North  Leeds,  and  for  the  rest  of  its  course  lies  near  that  railroad. 
Near  North  Leeds  outlyhig  ridges  appear  inclosing  kettleholes.  South- 
ward these  reticulated  ridges  become  lower  and  broader,  and  not  far  north 
of  Curtis  Corner,  in  Leeds,  they  coalesce  into  a  rather  level  plain  about 
one-fourth  of  a  mile  wide,  which  toward  the  south  expands  in  fan  shape  to 
the  breadth  of  1  mile,  and  the  material  becomes  finer  and  finally  passes 
into  sand  overlying  clay.  The  sand  ends  about  2  miles  south  of  Curtis 
Corner,  at  an  elevation  of  about  300  feet,  and  from  this  point  a  plain  cov- 
ered by  clay  extends  to  Sabatis  Pond,  and  so  on,  to  the  sea.  The  fan- 
shaped  plain  at  Curtis  Corner  is  plainly  a  delta. 

The  problem  as  to  the  extension  of  this  system  north  of  Chesterville 
is  complex.  For  years  before  I  had  worked  out  the  diagnosis  of  the  osar- 
plain  I  suspected  that  the  plain  of  well-rounded  gravel  extending  along  the 
valley  of  the  Sandy  River  from  Farmington  Falls  to  Phillips  was,  in  part 
at  least,  of  glacial  origin.  It  is  but  justice  to  add  that  I  passed  through 
this  valley  in  1879,  before  it  was  possible  for  me  to  distinguish  the  osar- 
plain  from  fluviatile  drift.  There  was  a  glacial  overflow  from  West  New 
Portland,  through  New  Vineyard,  down  a  small  stream  that  joins  the  Sandy 
River  a  mile  above  Farmington  Village,  and  there  was  another  from  King- 
field  to  Strong,  but  in  these  cases  the  only  recognizable  glacial  gravels  were 


CHESTEKVILLE-LEEDS  SYSTEM.  197 

small  kames  near  the  jaws  of  low  passes.  The  great  size  of  the  gravels  in 
Chester\'ille  demands  a  large  supply  of  water  from  the  north.  For  these 
reasons  I  consider  it  highly  probable  that  the  gravels  of  the  upper  valley 
of  the  Sandy  Eiver  are  partly  an  osar-plain  and  partly  an  overwash  or 
frontal  plain,  and  that  this  glacial  river  drained  a  large  area  north  of  Phillips 
and  south  of  Mount  Abraham.  From  Farmington  Falls  south  the  probable 
course  of  the  glacial  river  was  along  the  valley  of  Chesterville  Stream. 
The  relations  of  this  osar  system  to  sedimentary  clay  and  sand  are  inter- 
esting. From  Chesterville  south  this  system  is,  throughout  its  whole  course, 
flanked  and  partly  or  wholly  covered  by  a  broad  plain  of  sedimentar}-, 
bluish-gray  clay,  overlain  by  more  or  less  sand.  Toward  the  north  this 
clay  plain  connects  with  the  similar  plain  found  in  the  valley  of  the  Sandy 
River  by  two  low  vallej^s,  one  along  the  Chesterville  Stream  and  the  other 
lying  2  or  3  miles  east  of  it.  The  broad  Chesterville  plain  of  .sedimentary 
clay  connects  with  a  similar  plain  that  borders  the  Andi'oscoggin  River  by 
two  routes,  one  around  the  northern  base  of  Moose  Hill,  in  Jay,  and  the 
other  along  a  low  pass  that  leads  northwest  from  near  the  Camp  Ground  in 
East  Livermore.  Whether  the  water  flowed  from  the  Sandy  River  over 
into  the  Androscoggin  or  in  the  opposite  direction  is  uncertain;  possibly  the 
flow  was  alternately  in  opposite  directions,  as  the  flood  height  of  these 
rivers  varied.  South  of  the  Camp  Grround  the  clay  plain  bordering  the 
osar  is  continuous  with  that  of  the  Androscoggin  Valley,  as  far  as  North 
Leeds,  where  a  hill  intervenes  between  the  two  plains.  South  of  this  point 
we  have,  in  addition  to  the  Andi'oscoggin  plain,  two  other  plains  covered  by 
clay.  One  lies  directly  along  the  line  of  the  osar,  past  Curtis  Corner  to 
Leeds  Junction  and  Sabatis  Pond.  Another  is  from  1  to  3  miles  west  of 
the  last  named  and  occupies  the  eastern  base  of  Quaker  Ridge  in  Greene. 
A  short  distance  north  of  Greene  station  this  plain  turns  east  to  the  head  of 
Sabatis  Pond.  All  of  the  clay  plains  just  described  are  above  the  contour 
of  230  feet  except  at  their  south  ends,  near  Sabatis  Pond  and  Lewiston,  and 
near  Androscoggin  Pond.  Wherever  I  crossed  them  they  filled  the  valleys 
they  occupied  from  side  to  side,  as  if  they  were  valley  alluvium.  On  gen- 
eral grounds  we  might  expect  the  deposition  of  osar  border  clays  in  a  broad 
ice  channel  along  the  flanks  of  the  gravels,  but  if  such  were  deposited  they 
seem  to  be  lost  in  the  midst  of  the  fluviatile  clays  and  sands  that  were 
deposited  later.     It  will  require  some  nice  discriminations  in  order  to  mark 


198  GLACIAL  GEAVELS  OF  MAINE. 

out  in  the  field  the  limits  of  the  glacial,  fluviatile,  and  estuarine  diift  of  this 
region,  and  to  write  out  its  full  glacial  and  postglacial  history. 

Androscoggin  Pond,  in  Wayne,  furnishes  an  interesting  study.  To 
the  west  of  it  is  situated  the  clay  plain  (overlain  by  sand)  bordering  both 
the  osar  and  the  Androscoggin  River.  The  pond  is  so  nearly  on  a  level 
with  the  river  that  its  outlet  is  called  the  Dead  River.  In  time  of  flood 
the  water  of  the  Androscoggin  River  is  higher  than  the  pond,  and  the  flood 
rushes  with  violence  southeastward  into  the  lake,  carrying  so  much  sedi- 
ment that  a  large  delta  has  been  formed  on  the  western  shore  of  the  pond. 
Such  an  overfow  into  the  pond  would  be  much  more  vigorous  directly 
after  the  melting  of  the  ice  in  the  valley,  when  the  Andi'oscoggin  River 
stood  at  least  as  high  as  the  top  of  the  clay  plain  about  50  feet  above  its 
present  level.  Under  these  conditions,  why  was  there  not  a  much  larger 
delta  formed .  on  the  western  shore  of  the  lake  1  Or,  rather,  why  did  not 
the  whole  south  end  of  the  pond  fill  up?  It  could  not  have  been  from  lack 
of  sediment,  for  these  same  waters  covered  many  square  miles  to  the  south 
of  this  point  with  from  20  to  60  feet  of  clay  and  sand.  But  it  is  possible 
that  the  depression  where  the  pond  now  is  was  originally  so  deep  a  rock 
basin  that  even  a  sheet  of  clay  as  deep  as  the  plain  of  the  Androscoggin 
River  could  not  fill  it  up.  I  have  not  examined  all  parts  of  the  shore  of 
this  large  pond  (it  is  about  5  miles  long  and  3  or  4  miles  broad),  but  at 
several  points  I  did  not  find  evidence  that  there  had  been  deposition  to  such 
a  depth.  A  broad,  open  valley  extends  from  Androscoggin  Pond  north- 
ward through  Wayne  and  Fayette  into  Mount  Vernon  and  Vienna.  In 
late  glacial  time  there  would  be  a  flow  of  ice  down  this  valley  for  some 
considerable  time  after  the  general  ice  movement  had  ceased.  If  this  flow 
was  sufiiciently  rapid  to  replace  the  ice  as  fast  as  it  was  melted  at  the  east- 
ern margin  of  the  osar  channel  or  afterwards  by  the  waters  of  the  swollen 
Androscoggin  River  or  the  sea,  the  place  where  the  pond  now  is  may  have 
been  covered  by  ice  during  the  time  of  most  active  sedimentation.  This 
will  account  very  plausibly  for  the  fact  that  the  pond  did  not  fill  up. 
According  to  the  late  Hon.  J.  S.  Berry,  of  Wayne,  the  greatest  depth  of 
the  lake  is  about  60  feet,  and  over  most  of  the  lake  it  is  miich  less. 

A  nearly  north-and-south  ridge  of  glacial  gravel  is  found  a  short  dis- 
tance west  of  Leeds  Junction.  It  ends  at  the  south  in  a  series  of  short 
ridges  separated  by  intervals.     This  series  is  about  a  mile  in  length.     At 


CHESTEKFIELD-LEEDS  SYSTEM.  199 

one  place  this  gravel  has  been  excavated  by  the  Maine  Central  Railroad 
Company.  There  is  an  interval  of  at  least  3  miles  between  this  ridge  and 
the  delta-plain  at  Curtis  Corner,  which  forms  the  apparent  termination  of 
the  Chesterville-Leeds  system. 

About  4  miles  southeast  of  Leeds  Junction  a  large  mound  rises  in  the 
midst  of  the  large  swamp  at  the  north  end  of  Sabatis  Pond.  It  is  probably 
composed  of  glacial  gravel. 

At  various  points  along  the  shores  of  Sabatis  Lake  there  are  small  bars 
and  terraces  of  glacial  gravel  at  various  heights  above  the  lake  up  to  100 
feet.  The  material  is  but  little  waterworn  and  forms  a  thin  cap  of  semi- 
morainal  yet  water-washed  gravel  overlying  the  till.  It  is  uncertain  whether 
these  gravels  south  of  Curtis  Corner  are  any  part  of  the  Chesterville  sys- 
tem. I  provisionally  marked  them  as  distinct.  The  gravels  along  Sabatis 
Lake,  taken  in  connection  with  the  terminal  moraine  at  Sabatisville,  affoi-d 
some  prima  facie  evidence  of  a  local  glacier  moving  down  the  valley  of 
Sabatis  Lake,  which  is  bordered  by  hills  several  hundred  feet  high.  The 
shortness  of  the  moraine  shows  that  the  ice  movement  was  then  contined  to 
the  valley.  North  of  Sabatis  Pond  are  two  open  valleys,  along  which  the 
ice  could  easily  flow  on  a  descending  grade  to  Sabatisville.  One  opens 
northward  into  Monmouth,  the  other  extends  northwestward  through  Leeds 
toward  Wayne  and  East  Livermore.  After  the  general  movement  of  the  ice- 
sheet  had  ceased,  on  account  of  transverse  hills,  ice  could  still  for  a  time  con- 
tinue to  flow  in  these  favorable  valleys.  Such  a  local  tongue  of  ice  in  the 
valley  of  Sabatis  Lake  would  account  for:  (1)  the  terminal  moarine  at  Sabat- 
isville; (2)  the  water-washed  moraine  stuff  on  the  sides  of  the  hills  near  the 
lake  (i.  e.,  these  were  formed  along  the  margin  of  the  local  glacier);  (3)  the 
fact  that  the  basin  of  the  lake  was  not  filled  up  by  the  clays,  which  may  be 
due  in  part  to  the  fact  that  the  valley  was  filled  by  ice  till  a  rather  late  date. 
The  length  of  the  system  from  Chesterville  to  Curtis  Corner,  Leeds,  is  20 
miles.     This  portion  of  the  system  must  date  from  late  glacial  time. 

I  have  not  here  explicitly  classified  the  water  drift  of  the  Sandy  River 
above  Farmington  Falls  as  an  osar-plain  overlain  by  later  frontal  sediments. 
The  critical  reader,  however,  who  compares  this  system  with  those  of  the 
other  valleys  lying  eastward  at  the  same  distance  from  the  coast,  as,  for 
instance,  the  gravels  of  the  Carrabassett  and  upper  Kennebec  valleys,  will 
discern  that  the  sedimentary  drift  of  all  these  valleys  has  many  features  in 


200  GLACIAL  GRAVELS  OF  MAINE. 

common  and  probably  has  a  common  origin.  If  so,  a  glacial  river  once 
flowed  through  the  upper  Sandy  River  Valley  to  near  Farmington  Falls, 
and  thence  southward,  and  was  a  part  of  the  Chesterville-Leeds  system. 
It  deposited  a  somewhat  discontinuous  osar-plain  along-  this  route.  Subse- 
quently, as  the  ice  melted,  a  great  quantity  of  frontal  matter  was  poured 
out  into  the  open  Sandy  River  Valley  in  front  of  the  retreating'  glacier. 
The  floods  now  more  or  less  washed  away  and  reclassified  the  previously 
deposited  glacial  gravels,  and  flanked  and  covered  them  with  later  sedi- 
ments. The  finer  matter,  being  carried  southward,  formed  the  great  sed- 
imentary plain  that  borders  the  Sandy  River  from  near  Farmington  to  its 
mouth,  and  also  furnished  the  sediment  for  the  ovei-flows  through  Mercer 
and  Norridgewock  to  the  Kennebec  River,  also  that  through  Chester-\dlle 
to  the  Androscoggin,  and  thereby  helped  to  form  the  broad  clay-and-sand 
plains  of  Chester-salle,  Jay,  East  Livermore,  Leeds,  Greene,  etc.  In  other 
words,  these  great  clay  plains  situated  above  230  feet  are  frontal  plains,  com- 
posed of  the  glacial  mud  poured  out  from  the  diminished  glaciers  which 
yet  lingered  in  some  of  the  larger  valleys  in  this  region  and  covered  nearly 
all  the  country  situated  20  to  30  miles  to  the  north.  This  was  the  chief 
origin  of  the  mud,  no  matter  at  what  elcA'ation  the  sea  stood  at  this 
distance  from  the  coast.  At  the  place  of  deposition  this  fine  sediment  now 
forms  a  part  of  the  valley  sediments.^ 

FREEPORT    SYSTEM. 

This  is  a  short  system  appearing  to  begin  in  Brunswick  near  the 
southern  brow  of  a  broad  hill  of  granite,  a  short  distance  southeast  of 
South  Durham.  For  about  a  mile  it  is  a  nearly  continuous  ridge  with  a 
meandering  course  and  obscure  stratification.  The  gravel  here  is  but  little 
waterworn  and  has  a  morainal  aspect.  Going  southward,  we  find  the  stones 
more  rounded  and  the  series  becomes  discontinuous,  consisting  of  shoi't 
ridges  one-half  mile  or  less  in  length  and  separated  by  intervals  of  varying 
length  up  to  2  miles.  One  ridge  of  the  series  is  found  in  Freeport  Village, 
near  the  railroad  station.  The  size  of  the  ridges  and  hummocks  of  the 
series  decreases  toward  the  south.  The  last  of  the  series  seems  to  be  a  small 
bed  of  gravel  situated  about  a  mile  southwest  of  Freeport  Village.     Except 

1  The  sea  may  have  reached  to  Farmington,  and  these  great  plains  be  in  large  part  fluviatile 
marine  deltas.     This  I  now  (1893)  consider  probable. 


LEWISTON-DURHAM  SERIES.  201 

at  the  north  end,  this  series  hes  in  a  region  covered  by  marine  clay.     Its 
length  is  about  5  miles. 

A  small  plain  of  gravel,  cobbles,  and  rounded  bowlders,  which  appears 
to  have  no  connections,  is  found  about  2  miles  northwest  of  Freeport  Village. 
It  will  be  more  fuUy  described  later. 

LEWISTON-DURHAM    SERIES. 

This  is  a  discontinuous  series  of  short  ridges,  domes,  and  plains,  sepa- 
rated by  the  usual  intervals.  It  appears  to  begin  as  a  terrace  in  the 
southern  part  of  Greene,  a  short  distance  east  of  the  Androscoggin  River 
and  about  75  feet  above  it.  The  gravel  here  is  but  little  waterworu,  yet 
plainly  has  had  the  finer  detritus  washed  out  of  it.  From  this  point  the 
series  continues  along  the  left  bank  of  the  Androscoggin  River  through 
Lewiston  to  the  west  line  of  Durham,  but  for  2  miles  in  Auburn  a  nearly 
parallel  series  is  found  also  on  the  right  bank.  One  of  the  smaller  mounds 
of  this  series  is  found  in  the  city  of  Lewiston,  a  short  distance  from  the 
end  of  the  upper  wagon  bridge  between  Lewiston  and  Auburn.  It  is 
composed  of  well-rounded  gravel  and  cobbles. 

The  two  parallel  series  of  gravels  in  Lewiston  and  Auburn  are  found 
at  or  near  the  brow  of  the  steep  banks  on  each  side  of  the  river  channel. 
These  places  would  be  favorable  to  the  formation  of  crevasses  in  the  ice, 
and  the  appearances  indicate  that  a  subglacial  river  flowed  on  each  side 
of  the  valley,  and  that  they  united  into  one  stream  about  a  mile  east  of 
Lewiston.  The  domes  of  this  series  vary  in  height  from  a  few  feet  up  to 
100  feet.  They  are  covered  or  partly  covered  by  the  marine  clays  as  far 
north  as  Lewiston,  and  how  much  farther  is  uncertain.  The  lower  clay  at 
Lewiston  contains  various  marine  shells;  the  upper  clay  is  sparingly  fossil- 
iferous.  The  only  fossil  I  have  been  able  to  find  in  the  upper  clay  is  a 
marine  alga,  a  frond  of  sea  lettuce,  found  a  short  distance  north  of  the 
Androscoggin  River  in  Lewiston.  This  was  at  an  elevation  of  about  220 
feet.  When  the  sea  stood  at  the  contour  of  230  feet,  it  would  extend  2  or 
ndore  miles  above  Lewiston. 

The  condition  of  western  and  central  Maine  during  the  last  of  the  Ice 
period  proper  and  during  the  subsequent  time  when  the  ice  was  melted  over 
the  valleys  but  still  lingered  in  the  country  lying  to  the  north  will,  when 
fully  investigated,  form  the  basis  for  an  interesting  chapter  in  geological 


202  GLACIAL  GEAVELS  OF  MAINE. 

history.  In  connection  with  the  investigation  of  the  glacial  gravels,  I  have 
been  able  to  gather  many  facts  as  to  the  periods  in  question.  The  aspect 
of  the  coast  was  then  very  different  from  what  it  is  at  present.  The  sea 
certainly  extended  up  the  Kennebec  Valley  to  Madison,  and  up  the  Andros- 
coggin to  a  point  not  far  north  of  Lewiston,  and  in  both  valleys  it  may  have 
extended  several  miles  farther.  The  Sandy  River  from  Farmington  Falls 
eastward  was  from  1  to  5  miles  wide,  and  this  portion  of  the  valley  was 
probably  occupied  by  an  estuary.  The  Sandy  River  at  that  time  over- 
flowed southward,  as  before  stated,  or  arms  of  the  sea  extended  and  joined 
the  Androscoggin  in  Jay,  East  Livermore.  South  of  Livermore  Falls  the 
alluvial  plain  of  the  Androscoggin  was  between  2  and  3  miles  wide  for  a 
large  part  of  its  course  southward  to  the  sea.  At  the  present  day  the 
highest  stage  of  these  rivers  in  time  of  flood  affords  far  less  water  than  then 
flowed  in  them.  At  about  this  time  there  was  apparently  an  extensive 
overflow  of  the  Androscoggin  River  southward  from  Canton  through  a  low 
pass  in  the  western  part  of  Livermore  into  Turner,  where  it  joined  a  broad 
sheet  of  water  which  filled  the  valley  of  Twentymile  River  as  far  west  as 
Buckfield  and  overflowed  southward  from  Buckfield  Village  through  Minot 
into  a  similar  body  of  water  which  filled  the  valley  of  the  Little  Andros- 
coggin River  to  a  point  west  of  Mechanic  Falls.  A  line  of  clays  also  extends 
south  from  Turner  to  Lake  Auburn.  This  is  in  part  osar  border  clay,  but 
in  a  greater  part  is  an  overflow  of  the  Twentymile  River  after  the  ice  had 
melted.  All  these  were  probably  arms  of  the  sea.  For  the  greater  part  the 
broad  sheets  which  filled  these  valleys  extended  from  side  to  side  of  their 
valleys.  Apparently  the  ice  had  then  melted  in  the  valleys,  or  nearly  so. 
At  this  time  a  narrow  arm  of  the  sea  extended  from  the  Fair-ground, 
Lewiston,  eastward  along  a  low  valley  to  Crowleys  Junction,  where  it  con- 
nected with  the  sea  in  two  directions,  one  northeastward  to  Sabatisville,  the 
other  southeastward  to  Lisbon.  Tide  water  extended  up  the  A^alley  of  the 
Little  Androscoggin  River  several  miles  above  Auburn,  perhaps  as  far  as 
South  Paris.  Below  Lewiston  the  Androscoggin  Bay  of  that  period  was 
from  1  to  3  miles  wide,  and  in  Durham  a  strait  extended  southward  through 
Pownal  and  soon  opened  out  into  the  bay  10  to  20  miles  wide  which  then 
covered  the  valley  of  Royal  River.  The  whole  of  the  coast  region  of 
Maine  to  a  breadth  of  from  10  to  30  miles  was  then  submerged,  except  the 
higher  hills,  which  appeared  as  a  multitude  of  islands  off  the  coast.     The 


LEWISTON-DURHAM  SEEIBS.  203 

rivers  were  pouring  a  vast  body  of  muddy  water  into  the  sea,  and  extensive 
deltas  of  sand  and  clay  were  being  formed  off  the  coast  of  that  period. 
Above  the  sea  vast  rivers  occupied  the  valleys.  They  were  laden  with 
sediment,  and  rapidly  filled  up  their  valleys  with  alluvium  or  valley  drift. 
At  first  the  sediment  was  clay,  but  later  the  floods  were  higher,  or  the 
slopes  steeper,  and  sand  was  deposited  by  the  swifter  waters.  This  sand, 
being  poured  into  the  sea  by  the  Androscoggin  and  other  rivers,  was  car- 
ried far  and  near  by  the  tidal  currents  and  spread  over  the  previously 
deposited  marine  clays.  A  broad  area  of  delta  sands  brought  down  by  the 
Andi'oscoggin  at  this  time  extends  from  Lewiston  to  Brunswick  and  Tops- 
ham,  and  almost  to  Bath;  also  from  Durham  southward  to  Yarmouth. 
The  area  of  this  delta  sand  is  diversified  by  frequent  dunes  of  blown  sand. 
A  small  portion  of  the  sand  overlying  the  marine  clays  may  be  due  to 
erosion  of  the  till  by  the  sea.  But  this  sand  is  not  most  abundant  next  the 
high  hills,  and  there  is  no  body  of  beach  gravel  corresponding  to  the  sand. 
It  is  plainly  delta  sand  brought  down  by  the  Androscoggin,  which  not  only 
emptied  into  the  sea  near  Lewiston,  but  also  near  the  south  end  of  Sabatis 
Pond  by  way  of  Leeds. 

The  Lewiston  series  of  discontinuous  domes  and  mounds  ends  near 
the  west  line  of  Durham.  About  3  miles  soiithwest  of  this  point  another 
series  of  mounds  and  broad  plain-like  ridges  begins  and  extends  past  West 
Durham  into  the  northern  part  of  Pownal,  where  the  series  ends,  unless  a 
small  ridge  near  Pownal  Center  be  a  connection  of  the  series.  Here,  in 
Lewiston,  Durham,  and  Pownal,  are  illustrated  the  difficulties  of  classifying 
glacial  gravels.  According  to  general  analogy,  the  gravel  systems  end 
in  either  a  delta-plain  or  they  become  discontinuous  and  form  a  series  of 
short  ridges  and  domes,  which  become  smaller  and  smaller  toward  the 
south,  and  the  intervals  between  them  longer  and  longer.  The  Lewiston 
series  ends  in  the  manner  last  mentioned  near  the  Androscoggin,  in  the 
northwestern  part  of  Durham,  and  the  West  Durham  series  ends  in  the 
same  way  in  Pownal.  These  series  are  situated  nearly  in  the  same  straight 
line,  and  the  interval  between  them  is  less  than  3  miles — facts  which  favor 
the  theory  that  they  are  a  continuation  of  the  same  system  and  were  depos- 
ited by  the  same  glacial  river.  But  each  series  ends  in  a  way  characteristic 
of  the  terminations  of  the  independent  systems,  and  I  therefore  hesitate  to 


204  GLACIAL  GRAVELS  OF  MAINE. 

assign   them  to  a  single    glacial   river,   although  the   same   river   can  be 
conceived  as  running  two  independent  careers  at  different  times. 

The  vicinity  of  Lewiston  is  a  favorable  locality  for  studying  the  dif- 
ferences between  the  glacial  gravels  and  the  valley  drift.  Only  two  theories 
can  be  admitted  as  accounting  for  the  ridges  and  mounds  of  gravel  and 
cobbles  of  the  Lewiston  series — they  are  either  glacial  gravel  or  they  are 
nneroded  fragments  of  an  ancient  sheet  of  valley  alluvium. 

1.  From  Bethel  to  the  sea  the  alluvium  of  the  upper  terraces  of  the 
Androscoggin  Valley  is  in  general  either  sand  or  clay.  For  a  short  distance 
below  where  the  river  has  cut  through  ridges  of  till,  there  are  limited  areas 
of  gravel,  also  at  the  parts  crossed  by  glacial  gravel  systems  or  near  the 
months  of  the  swifter  tributaries.  Low  terraces  of  sand  and  gravel  are 
found  along  the  banks  of  the  river,  reaching  5  or   10  feet  above   it,  but 

nowhere  below  Bethel  does  the  low  flood- 
_^^i5iiJ!_j2fL_-^:^l_Ilol£Ilool     plain   terrace    contain    any   such    rounded 

cobbles  or  bowlderets  as  are  found  in  the 

ridges  of  the  Lewiston  series,  except  where 

crossed  by  osars  and  near  the  mouth   of 

„     Swift  River.     The  stones  of  the  flood-plain 

terrace  and  those  in  the  bed  of  the  river 

^    are  not  nearly  so  much  rounded,  and  many 

'■'Z>   ^  oXo^\    Qf  them  have  till  shapes,  with  but  little 

Fig     1  — tjtrat  float  on  of  lent  c  lar  gravel 

modification  by  water  action 

2.  The  two-sided  ridges  and  mounds  of  gravel,  cobbles,  and  bowl- 
derets of  the  Lewiston  series  cover  but  a  small  part  of  the  valley — here 
and  there  a  dot,  so  to  speak.  If  they  are  nneroded  portions  of  a  sheet  of 
similar  matter  which  formerly  filled  the  valley  to  a  heig'ht  of  about  100 
feet,  then  there  has  been  a  vast  erosion  of  coarse  matter  from  the  valley, 
and  this  ought  to  appear  as  plains  of  such  material  in  Brunswick  and  Bow- 
doinham  and  along  the  shores  of  Merrymeeting  Bay,  where  the  Andros- 
coggin unites  with  the  Kennebec.  But  those  regions  show  only  fine 
sediments — sand  and  clay. 

Two-sided  ridges  and  domes  rising  50  to  100  feet  above  the  level 
ground  on  all  sides  of  them  can  not  be  any  form  of  beach  terrace  or  sea 
wall.  Their  forms  and  situations  make  this  impossible.  In  short,  these 
gravels  can  not  be  au}^  form  of  marine  or  ordinary  fluviatile  drift. 


LEWISTON  DURHAM  SEKIES. 


205 


The  length  of  the  Lewiston  series  is  9  miles;  that  of  the  West  Durham 
series,  5  miles. 

HILLSIDE    ESKERS    IN    JAY   AND    WILTON. 

About  1^  miles  south  of  Beans  Corner,  in  Jay,  is  a  good  specimen  of 
the  short  sidehill  systems  as  they  appear  in  a  region  of  granite  rock.  Four 
parallel  ridges  begin  on  the  rather  steep  southern  slope  of  a  hill  and  extend 
about  one-foui'th  of  a  mile  southward  to  the  base  of  the  hill,  where  they 
expand  into  low  broad  ridges  and  then  appear  to  end  in  a  dome  of  coarse 
matter.  To  the  south  and  east  are  some  rather  level  till-covered  fields,  and 
then  the  great  clay-covered  plain  of  Jay  and  Chesterville,  but  I  could  trace 
the  glacial  gravel  no  farther  in  that  direction.  The  ridges  are  composed  of 
a  mixture  of  gravel  and 
large  stones  of  all  sizes, 
up  to  bowlders  3  feet  in 
diameter.  The  finer  de- 
tritus has  been  washed  c 
away,  but  the  stones  are  a\; 
hardly  more  rounded  '^ay^op^S'S'S>± 
than  those  of  the  terminal 
moraines  of  the  local 
Androscoggin  glacier  in 
Grilead  and  Shelburne. 
The  hillside  systems  usu- 
ally become  finer  in  composition  at  their  south  ends,  where  they  terminate 
in  a  sort  of  delta,  but  in  this  case  the  ridges  are  composed  of  coarse  matter, 
even  to  their  extremities.  The  large  size  of  the  contained  bowlders  favors 
the  interpretation  that  these  ridges  were  deposited  beneath  the  ice. 

Another  short  system  begins  at  the  top  of  the  hill  which  lies  directly 
south  of  Wilton  Village,  and  extends  for  somewhat  more  than  a  mile  south- 
ward, into  Jay,  on  the  slopes  of  a  long  hill.  Its  course  lies  along  the  bot- 
tom of  a  ravine  100  to  150  feet  wide,  which  is  bordered  by  steep  banks  of 
till  10  to  30  feet  high.  The  gravel  forms  a  terrace  lying  against  and  upon 
the  till  which  forms  the  eastern  bank  of  the  ravine.  On  the  west  side  the 
bottom  of  the  ravine  is  quite  level  and  covered  with  soil  finer  in  composi- 
tion than  the  surface  till  of  the  surrounding  country.  It  is  either  a  very 
clayey  till  or  a  sedimentary  clay  into  which  some  tillstones  have  been 


Fig.  22. — Stratification  of  lenticular  gravel,    a,  a,  very  obscurely  stratified 
portions  of  kame,  almost  pellmell  in  structure. 


206  GLACIAL  GKAVELS  OF  MAINE. 

washed  by  the  rains  or  other  means.  At  the  base  of  the  hill  (after  a  fall  of 
about  100  feet)  the  gravel  spreads  ont  into  a  narrow  fan-shaped  series 
of  several  ridges  situated  side  by  side.  These  ridges. extend  a  short  dis- 
tance out  into  the  valley  of  a  small  stream  which  flows  south  westward  into 
the  Androscoggin  River.  This  valley  is  covered  by  a  sheet  of  sedi- 
mentary clay  and  coarse  sand  to  a  breadth  of  one-fourth  of  a  mile.  These 
sediments  overlie  the  glacial  gravel  ridges.  On  the  south  they  are  con- 
tinuous with  the  high  alluvial  terraces  of  the  Androscoggin. 

The  ravine  on  the  side  of  the  hill  must  be  accounted  for.  The  till  of 
this  portion  of  Franklin  County  is  collected  into  a  great  number  of  long 
lenticular  masses  with  smooth  outlines,  and  is  remarkably  free  from  steep 
ridges  or  hummocks  or  depressions.  This  ravine  has  every  appearance  of 
having  been  cut  into  the  deep  sheet  of  till  which  covers  the  hillside.  No 
stream  flows  in  this  ravine  except  in  time  of  rains,  and  the  ravine  reaches 
to  the  top  of  the  hill.  The  ridges  at  the  bottom  of  the  hill  have  steep 
slopes  on  both  sides,  and  could  not  be  formed  as  a  delta  at  its  base  by  an 
ordinary  surface  stream  eroding  the  till  on  the  hillside  and  sweeping  the 
eroded  matter  down  into  the  valley.  Usually  the  glacial  gravel  is  piled 
above  the  surroiuiding  level,  and  there  is  no  evident  depression  showing-  an 
erosion  of  the  till,  betraying  where  the  kame  stuff  came  from.  But  here, 
as  in  several  other  places,  a  channel  with  steep  lateral  banks  is  cut  into  the 
till.  A  fair  inference  from  all  the  facts  is  that  a  stream  flowing  between  ice 
walls  here  flowed  down  the  hill  and  eroded  the  ravine  in  the  till  and  carried 
the  material  down  into  the  valley.  The  terminal  ridges  must  have  been 
formed  between  ice  walls.  Beyond  the  ridges  the  plain  of  alluvium  in  the 
valley  may  be  in  pai't  composed  of  the  finer  sediment  brought  down  by 
this  small  glacial  stream,  if  the  stream  dates  from  a  late  j^eriod  when  the 
ice  Avas  retreating  up  the  valley,  as  was  probably  the  case. 

CANTON-AUBURN  SYSTEM. 

A  broad  mountain  cirque  between  high  hills  is  situated  in  Weld,  Car- 
thage, Mexico,  and  Dixfield.  This  valley  is  drained  southward  into  the 
Androscoggin  River  at  Dixfield.  Considerable  alluvium  is  found  in  the  val- 
ley, most  of  which  appears  to  be  valley  drift,  i.  e.,  frontal  overwasli,  but 
with  some  signs  of  an  osar-plain  along  the  axis  of  the  valley;  and  tlie  same 
can  be  said  of  the  valley  of  Swift  River  in  Byron,  Roxbury,  Rumford, 


CANTON-AUBUEF  SYSTEM.  207 

and  Mexico;  and  perhaps  there  should  be  added  the  Androscoggin  Valley 
from  the  mouth  of  Swift  River  to  Canton.  There  has  been  a  large  amount 
of  erosion  along  the  Androscoggin  and  Swift  rivers,  and  this  makes  It 
doubly  difficult  to  discover  what  was  the  original  condition. 

A  well-developed  osar-ridge  begins  not  far  from  the  Androscoggin 
.River  at  Gilbertville  (Canton  Point),  and  passes  southward  throug'h  the 
wide  plain  covered  by  sedimentary  clay  and  sand  which  here  borders  the 
Androscoggin  on  the  soiitli.  It  passes  about  half  a  mile  east  of  Canton 
Village,  and  then  ascends  the  valley  of  Bog  Brook  to  its  source  at  a  small 
pond  in  Livermore.  In  this  valley  the  gravel  takes  a  somewhat  unusual  form. 
A  two-sided  ridge  is  found  along  the  axis  of  the  valley,  bordered  on  each  side 
by  a  ravine  of  erosion,  while  on  each  side  of  the  valley  is  a  level  terrace  of 
fine  gravel.  The  central  ridge  consists  of  gravel  with  cobbles  and  bowl- 
derets,  all  very  much  rounded.  It  rises  10  to  20  feet  above  the  terraces  at 
the  sides  of  the  valley.  Evidently  a  glacial  stream  at  one  time  flowed  in  a 
rather  narrow  channel  in  the  midst  of  the  valley,  and  in  this  naiTow  chan- 
nel was  deposited  the  central  ridge  of  coarse  matter.  Later  the  channel 
widened  until  it  extended  nearly  or  quite  across  the  valley,  and  in  this 
broad  channel  the  finer  gravel  was  deposited  as  a  plain  extending  from  the 
central  ridge  to  each  side  of  the  valley.  The  current  in  the  broad  channel 
was  not  so  rapid  as  in  the  narrow  one,  and  the  gravel  was  finer  and  did  not 
reach  to  so  great  a  height  as  the  original  osar.  Finally  valleys  of  erosion 
have  been  excavated  in  the  osar-plain  along'  each  flank  of  the  osar. 

In  several  places  the  terraces  along  the  sides  of  the  valley  can  be  seen 
to  overlie  till.  Many  bare  ledges  appear  in  the  southern  part  of  the  pass, 
as  if  the  till  had  been  washed  away  by  the  glacial  river.  The  top  of  this 
pass  is  so  level  that  for  a  considerable  distance  we  find  a  stream  flowing 
northward  on  one  side  of  the  osar  ridge  and  on  the  other  side  a  stream 
flowing  in  the  opposite  direction. 

On  the  west  and  southwest  sides  of  Brettuns  Pond,  at  Livermore  Post- 
Office,  the  gravel  takes  the  form  of  a  narrow  plain  of  reticulated  ridges  and 
hummocks  of  gravel,  cobbles,  and  bowlderets.  Extending  from  this  plain 
eastward  around  the  south  end  of  the  pond  is  a  rather  level  plain  composed 
of  gravel  on  the  west  but  becoming  sand)^  toward  the  east.  It  is  aboiit 
one-third  of  a  mile  in  diameter,  and  is  evidently  a  delta-plain.  It  lies 
between  Brettuns  Pond  and  the  valley  of  Martins  Stream.     This  valley  is 


208  GLACIAL  GRAVELS  OF  MAIlsE. 

widely  covered  by  sedimentary  clay  from  Livermore  Center  eastward  to 
Livermore.  The  cuiTents  which  deposited  the  delta  south  of  Brettuns 
Pond  must  have  flowed  for  near  a  mile  along-  the  west  and  southwest  sides 
of  the  pond,  bordering  it  with  liigh,  steep  banks  of  gravel,  cobbles,  and 
bowlderets.  If  the  area  where  the  pond  now  is  had  been  bare  of  ice  at 
the  time  these  waters  flowed  south  from  Canton,  the  delta  would  have 
been  formed  where  the  pond  now  is.  The  facts  indicate  that  the  valley  of 
Martins  Stream  was  occupied  by  a  glacial  lake  or  other  body  of  water  at 
the  time  this  delta  was  formed,  while  the  area  where  the  pond  now  is  must 
have  been  occupied  by  ice.  The  finer  sediment  brought  down  by  the 
glacial  stream  passed  beyond  the  delta  of  gravel  and  sand,  and  furnished 
the  clay  which  covers  this  valley. 

A  rather  level  osar-plain,  from  one-eighth  to  one-half  of  a  mile  wide, 
extends  along  the  valley  of  Martins  Stream  southward  nearly  to  the 
Twenty  mile  River.  Between  Livermore  and  North  Turner  the  plain  has 
been  irregularly  eroded  so  as  to  leave  a  marginal  terrace  on  each  side  of 
the  valley  and  a  ridge,  or,  rather,  series  of  ridges  arranged  as  a  single  line 
in  its  midst.  These  ridges  appear  as  narrow  islands  in  the  midst  of  the 
artificial  pond  (produced  by  the  dam  at  North  Turner),  which  now  occupies 
the  valleys  of  erosion  on  each  side  of  the  central  ridge.  The  central  ridge 
here  has  the  same  height  as  the  marg'inal  terraces,  except  where  it  has  been 
reduced  by  erosion.  South  of  North  Turner  the  osar-plain  is  bordered  by 
a  wide  plain  covered  by  sedimentary  clay,  overlain  by  some  sand.  This 
allu^dal  plain  is  connected  with  the  plain  of  sedimentary  clay  that  covers 
the  valley  of  Twentymile  River  by  two  lines  of  clays,  one  southward 
down  the  valley  of  Martins  Stream,  the  other  southeastward  past  the  west 
side  of  Pleasant  Pond  and  then  by  a  low  pass  to  Bradford  Village  (Turner 
Center).  I  could  find  no  glacial  gravel  along  the  last-named  route,  and 
infer  that  this  large  area  of  fine  sediment  was  not  deposited  in  a  broad 
osar  channel,  but  at  a  time  when  the  lowlands  were  all  bare  of  ice  and 
covered  with  water,  probably  either  fluviatile  or  estuarine. 

The  osar  terrace  becomes  finer  as  it  nears  the  Twentymile  River, 
and  thus  shows  some  of  the  characters  of  the  delta-plain.  It  appears 
to  be  interi-upted  for  a  half  mile  or  more  near  Twentymile  River,  but 
soon  begins  again  as  a  series  of  low  reticulated  ridges  or  plains  from 
one-fourth  to   one-half  of  a  mile  broad.     The  reticulated  plains  extend 


CAHTOiSr-AUBURN  SYSTEM.  209 

southward  along-  a  low  pass.  They  inclose  several  lakelets,  some  without 
visible  outlets.  Toward  the  south  the  ridges  coalesce  into  a  level  plaiu,  the 
materials  of  which  become  finer,  the  gravel  passing  by  degrees  into  fine 
sand,  and  this  into  sedimentary  clay  about  a  mile  north  of  the  northeast 
angle  of  Lake  Auburn.  This  clay  extends  along  the  east  side  of  the  lake 
and  thence  to  Auburn  and  Lewistou,  where  it  is  plainly  marine.  A  little 
silt  or  clay  is  found  in  the  valleys  of  the  small  brooks  which  flow  into  Lake 
Auburn,  which  is  probably  valley  or  lake  drift.  With  these  insignificant 
exceptions,  the  only  clay  found  along  the  shores  of  the  lake  is  that  found 
along  tlie  northeastern  side,  where  a  plain  of  fine  blue  clay  rises  30  feet 
above  the  lake  and  apparently  forms  part  of  the  barrier  that  holds  it  back. 
If  Lake  Auburn  was  bare  of  ice  or  was  occupied  by  an  open  arm  of  the 
sea  at  the  time  this  clay  was  being  laid  down,  the  clay  ought  to  have 
extended  farther  west,  probably  all  around  the  lake.  The  water  which 
poured  south  from  Turner  was  certainly  muddy,  as  is  shown  by  the  great 
de^itli  of  clay  at  the  northeast  angle  of  the  lake.  This  makes  it  highly 
probable  that  the  clay  was  deposited  in  a  broad  channel  within  the  ice  at  a 
time  when  the  area  which  Lake  Aubui-n  now  occupies  was  covered  by  ice. 

No  gravel  rises  above  the  clay  for  about  2  miles,  and  then  we  find  a 
rather  level  gravel  plain  near  the  southeast  angle  of  Lake  Auburn.  It  is 
about  a  mile  long  and  more  than  half  as  broad.  The  gravel,  cobbles,  and 
bowlderets  of  which  it  is  composed  at  its  north  end  are  not  much  water- 
Avorn,  and  often  have  almost  a  till  shape.  Toward  the  south  and  east  the 
material  is  somewhat  finer  and  the  plain  appears  to  be  a  delta  deposited 
either  in  a  bay  of  the  sea  that  was  inclosed  between  ice  walls  or  in  a  glacial 
lake.  About  half  a  mile  south  of  this  is  another  similar  one.  It  ends  in 
steep  banks  on  all  sides  except  one,  where  it  lies  like  a  terrace  against  a 
hill.  This  plain  is  only  about  one-fourth  of  a  mile  in  diameter,  and  becomes 
sandy  on  the  south  and  east  aides,  and  is  thus  shown  to  be  an  incomplete 
delta. 

South  of  this  point  I  have  been  able  to  find  no  glacial  gravel  for  about 
8  miles.  The  system  ends  on  a  hill  overlooking  the  valley  of  the  Little 
Androscoggin.  The  system  dates  from  a  time  when  the  sea  had  advanced 
up  the  valleys  of  the  Androscoggin  and  Little  Androscoggin  to  a  jaoiut 
some  distance  west  of  Aubm-n.  The  ice  still  lingered  to  the  north.  Three 
delta-plains  were  formed  in  AiTburn  during  the  flow  of  this  large  glacial 

MON  XXXIV li 


210  GLACIAL  GRAVELS  OF  MAINE. 

stream,  and  perhaps  a  fourth  was  afterwards  formed  iii  Turner  north  of  the 
Twenty  mile  River.  For  many  miles  this  great  osar  river  flowed  in  a  chan- 
nel one-eighth  to  one-half  of  a  mile  wide.  In  this  channel  was  deposited 
a  level  plain  of  rather  fine  gravel  of  the  type  which  I  have  named  the  osar- 
plain.  Whenever  the  system  expands  into  plains  of  reticulated  ridges  the 
material  is  very  coarse.  The  very  great  size  of  the  glacial  river  which 
flowed  south  from  Canton  makes  it  highly  probable  that  it  drained  the  val- 
levs  lying  north  and  northwest  from  it,  including  Swift  River.  If  so,  the 
oi'iginal  gravels  have  been  much  disguised  by  later  sediments.  Indeed,  we 
might  expect  that  during  the  retreat  of  the  ice  there  would  come  a  time 
when  the  ice  was  melted  over  the  Androscoggin  Valley  but  still  lingered 
toward  the  north,  and  overwash  or  frontal  plains  would  at  this  time  be 
brought  down  into  the  main  valley  and  cover  out  of  sig'ht  much  of  the 
earlier  sediment. 

The  length  of  the  system  from  Canton  to  Auburn  is  about  25  miles. 

NOTE  ON  THE  ANDROSCOGGIN  VALLEY. 

For  about  60  miles  from  Gorham,  New  Hampshire,  to  Jay,  the  direc- 
tion of  the  Androscoggin  River  is  a  little  north  of  east.  It  is  a  valley  of 
preglacial  erosion  excavated  in  highly  crystalline  rocks,  chiefl}'  granite. 
On  each  side  of  the  river  the  hills  rise  steeply,  becoming  higher  as  the 
White  Mountains  are  approached.  The  river  is  bordered  by  a  jjlain  of 
valley  drift,  Avhich  for  most  of  its  course  is  less  than  half  a  mile  in  breadth, 
but  here  and  there  spreads  out  into  much  broader  intervals,  1  to  3  miles 
wide.  Such  a  plain  is  found  in  Canton.  About  3  miles  east  of  Canton  the 
river  has  cut  through  a  sheet  of  till  70  feet  thick.  This  body  of  till 
dammed  the  river  in  the  Valley  Drift  period  and  formed  a  lake  where  the 
broad  Canton  intervale  now  is.  It  is  probable,  but  not  certain,  that  this 
raised  the  level  of  the  Androscoggin  sufficiently  to  cause  an  overflow  south- 
ward to  Livermore  along  the  Bog-  Brook  Pass.  As  already  noted,  the 
valley  drift  of  the  Androscoggin  is  noticeable  for  its  fineness  over  most  of 
the  course  of  the  river. 


HILLSIDE   ESKERS   IN   HARTFORD. 


Whitney   Pond  lies   a  short   distance    southwest  of    Canton  Village. 
About  a  mile  north  of  this  pond,  on  the  road  from  Canton  to  Sumner,  are 


PEEU-BUCKFIELD  SYSTEM.  211 

two  slioi't  systems  of  sidehill  kames  or  eskers.  They  are  situated  in  small 
north-aud-south  valleys  wluch  descend  steeply  toward  the  south.  The 
ridges  begin  on  the  hillside,  and  after  descending  about  100  feet  to  rather 
level  ground,  they  end  within  a  mile  in  small  delta-plains.  At  their  north 
end  the  ridges  do  not  have  the  smooth  and  arched  cross  section  so  common 
to  kame  ridges  found  near  the  present  sea  level,  but  they  have  the  steeper 
lateral  slopes  and  the  irregular  heaping  characteristic  of  the  lateral  moraines 
of  a  local  or  valley  glacier.  The  material  has  been  but  little  polished  by 
water,  yet  the  finer  drift  has  been  washed  out  of  it.  The  two  systems  are 
only  about  a  mile  apart.  The  western  system  consists  of  three  parallel 
ridges  which  become  confluent  in  the  terminal  plain. 

PERU-BUCKFIELD   SYSTEM. 

Worthley  Pond,  Peru,  lies  in  a  narrow  valley  bordered  by  steep,  high 
hills.  The  outlet  of  the  pond  flows  northeastward  into  the  Andi'oscoggin 
River  at  South  Peru.  South  of  the  pond  the  valley  narrows  so  as  to  form 
an  almost  V-shaped  pass  through  the  high  hills  which  lie  not  far  south  of 
the  Androscoggin  River.  The  highest  part  of  this  pass  is  situated  only  a 
short  mile  south  of  Worthley  Pond  and  about  100  feet  above  it.  South  of 
the  pond,  in  the  bottom  of  this  narrow  valley,  are  several  short  ridges  of 
sand  separated  by  gaps.  Only  a  small  brook  flows  in  the  valley,  and  it  is 
quite  incapable  of  depositing  ridges  such  as  these,  in  respect  either  to 
form  or  to  size.  Lying  across  this  part  of  the  valley,  or  forming  irregular 
terraces  along  the  lower  slopes  of  the  bordering-  hills,  are  numerous  piles 
and  heaps  of  sandy  till  which  have  the  appearance  of  moraines  of  a  local 
glacier.  Probably  a  tongue  of  ice  ptrojected  south  through  the  jjass  in  late 
glacial  time  and  left  these  moraines  during  its  retreat  northward.  During 
the  retreat  of  the  ice  front  down  the  northern  slope,  a  small  lake  would 
naturally  form  between  the  ice  and  the  hill  to  the  south.  The  drainage  of 
the  local  glacier  would  pour  into  this  small  lake  and  then  overflow  south- 
ward over  the  col.  If  a  large  stream  flowed  into  such  a  lake,  the  whole 
valley  ought  to  be  deeply  covered  by  a  lake  delta.  On  the  contrary,  the 
sand  and  fine  gravel  are  found  in  the  form  of  several  isolated  ridges.  This 
seems  to  indicate  that  the  sand  ridges  were  deposited  by  small  streams  in 
channels  within  the  ice,  and  that  after  the  formation  of  the  lake  at  the  ice 
front  there  ^vas  eitlier  little  sediment  or  the  drainao-e  flowed  northeastward 


212  GLACIAL  GRAVELS  OF  MAINE, 

to  the  Androscoggin.     I  could  iind  no  proof  that  these  sand  ridges  were 
nneroded  portions  of  a  delta  that  once  filled  the  valley. 

No  kame  material  was  found  for  a  short  distance  near  the  top  of  the 
pass,  and  then  begins  a  series  of  low  ridges  and  terraces  of  fine  gravel  con- 
taining but  few  large  stones,  and  those  are  but  little  polished  by  water.  In 
numerous  places  these  deposits  could  be  seen  to  consist  of  a  thin  sheet  of 
gravel  (2  to  5  feet  thick)  overlying  the  till.  All  these  facts  combine  to 
prove  that  the  glacial  stream  that  flowed  south  throiigh  the  Worthley  Pond 
Pass  was  very  small,  compared  with  the  mighty  rivers  which  flowed  out  of 
the  Androscoggin  Valley  at  Canton  and  Rumford.  The  system  follows  the 
valley  of  the  main  east  branch  of  Twentymile  River  to  Sumner  station 
(Sumner  Flats),  and  then  its  course  lies  near  the  railroad  to  a  point  near 
Buckfield  Village.  The  gravel  appears  as  low,  rather  level-topped  ridges, 
like  a  narrow  osar-plain,  except  that  they  inclose  some  shallow  kettleholes. 
Often  these  plains  appear  like  terraces  on  the  sides  of  the  valley,  and 
erosion  of  the  central  parts  of  the  plain  by  the  stream  often  increases  this 
resemblance.  The  system  is  somewhat  interrupted  by  short  gaps  north  of 
Sumner  station.  South  of  that  point  the  separate  ridges  coalesce  more  and 
more,  and  not  far  north  of  Buckfield  the  system  passes  into  a  delta-plain 
one-fourth  to  one-half  mile  wide.  The  sand  of  the  delta  passes  by  degrees 
into  the  clay  which  covers  the  valley  of  the  Twentymile  River  all  the  way 
from  its  mouth  to  a  point  several  miles  above  Buckfield.  At  a  few  points 
not  far  south  of  Sumner  excavations  showed  that  a  number  of  low  ridges 
had  first  been  deposited  in  a  separate,  narrow  channel,  bordered  by  ice 
walls.  Subsequently  the  depressions  between  the  ridges  were  filled  up  so 
as  to  make  of  the  whole  a  level-topped  plain.  Probably  the  tops  of  the 
original  ridges  were  in  part  washed  away  by  the  broad  body  of  water 
which  at  the  last  swept  over  the  whole  breadth  of  the  gravel  system,  and 
may  have  furnished  part  of  the  material  to  fill  up  the  depressions.  This  is 
a  sort  of  structure  to  be  anticipated  for  the  osar-plains,  but  in  this  case  the 
plain  extends  across  the  valley  from  side  to  side  in  such  a  manner  as  to 
make  it  difficult  to  judge  whether  this  plain  was  deposited  in  a  broad 
channel  within  ice  walls  or  in  the  open  valley  after  the  ice  had  melted. 
Even  if  the  upper  part  of  the  plain  be  valley  drift  of  less  age  than  the  ice 
occupancy  of  that  region,  the  underlying  ridges  are  plainly  contempo- 
i-aneous  with  the  ice  occupancy. 


WEST  POLAlSTD-STTMiSrEE  SYSTEM.  213 

The  delta-plain  northeast  of  Bucktield  Village  has  been  deeply  eroded 
by  streams  and  springs.  At  one  place  a  long  ridge  has  been  left  imeroded. 
It  is  locally  known  as  the  "  Whalesback."  On  the  surface  it  appears  to  be 
composed  of  nearlj^  horizontally  stratified  sand  and  gravel  like  the  rest  of 
the  delta,  yet  there  must  be  some  reason  why  this  portion  of  the  plain  has 
resisted  erosion,  and  it  may  be  there  is  a  ridge  of  coarse  kame  stuff  along 
the  axis  of  this  "Whalesback."  Evidently  this  delta  dates  from  a  late  period, 
when  the  ice  had  melted  as  far  north  as  this  place. 

-  The  apparent  end  of  this  system  northeast  of  Buckfield  is  only  about 
a  mile  from  the  West  Sumner-Poland  system.  It  is  therefore  possible — 
perhaps  probable — that  they  were  at  one  time  connected,  but  thus  far  I  am 
iinable  to  prove  it.  The  Peru  glacial  river  may  have  joined  that  from  West 
Sumner  by  flowing  southwest  from  the  above-mentioned  delta-plain  through 
Buckfield  Village  or  along  a  very  low  valley  situated  about  a  mile  farther 
east.  These  valleys  are  all  so  deeply  covered  by  sedimentary  clay  that 
only  large  deposits  of  glacial  gravel  would  rise  above  the  surface.  This 
clay  is  probably  of  estuarine  origin. 

The  length  of  the  system  from  Worthley  Pond  to  Buckfield  is  13  miles. 

WEST  SUMNER-POLAND  SYSTEM. 

This  system  appears  to  begin  about  a  mile  south  of  West  Sumner,  in 
the  form  of  an  osar-ridge  which  follows  the  valley  of  the  west  branch  of 
Twentymile  River  for  several  miles  and  then  expands  into  a  delta-plain  a 
short  distance  west  of  Buckfield  Village.  From  this  point  a  broad,  low 
valley  extends  southward,  to  Mechanic  Falls.  Along-  this  valley  the  railroad 
is  constructed.  The  bottom  of  the  valley  is  covered  with  sedimentary  clay, 
continuous  on  the  north  with  the  clay  of  the  valley  of  Twentymile  River 
and  on  the  south  with  that  of  the  Little  Androscoggin  Valley.  A  series  of 
low  ridges,  terraces,  and  deposits  of  glacial  gravel  resembling  the  broad 
osar  is  found  along  the  valley  its  whole  length.  Near  Buckfield  the  gravels 
skirt  the  base  of  the  high  hills  Ij'ing  west  of  this  valley,  near  East  Hebron 
they  lie  in  the  midst  of  the  pass,  and  at  West  Minot  they  are  on  the  west 
side  again.  As  we  approach  Mechanic  Falls  the  gravels  rise  out  of  the 
valley  and  are  found  on  the  slopes  of  the  hills  on  the  east  side.  There  are 
several  apparent  short  gaps  in  the  series.  The  intervals  are  more  frequent 
toward  the  south  and  the  deposits  become  narrower  and  finally  form  simple 


214  (ILACIAL  GRAVELS  OF  MAINE. 

eskers  not  at  all  plain-like.  Neai-  the  Little  Androscogg'in  River  there  is 
apparently  a  long-  interval  of  2  miles  where  there  is  no  gravel.  About  2 
miles  east  of  Mechanic  Falls  is  a  sand-and-gravel  plain  in  Poland,  which 
extends  for  more  than  2  miles  southeastward,  near  the  line  of  the  Grrand 
Trunk  Railway.  The  plain  becomes  finer  on  the  east  and  south  edges,  and 
passes  by  degrees  into  sand  and  at  last  into  the  clay  which  covers  the 
valley  of  the  Little  Androscoggin  from  Auburn  many  miles  west.  These 
plains  in  Poland  are  a  delta,  but  it  is  uncertain  whether  they  were  formed 
in  a  glacial  lake  or  in  the  broad  body  of  sea  water  which  subsequently 
covered  Little  Androscoggin  Valley. 

Subsequent  to  the  melting  of  the  ice  there  was  an  overflow  from  the 
valley  of  the  Little  Androscoggin  southeastward  along  a  low  pass,  past 
Danville  Junction.  There  are  several  mounds  of  true  glacial  gravel  in  the 
valley  of  Royal  River  in  New  Gloucester.  These  are  properly  situated 
to  be  branches  of  either  the  Canton-Auburn  or  the  West  Sumiier-Poland 
system,  but  I  have  been  able  to  trace  no  connection  between  them,  although 
the  Danville  Junction  Pass  is  a  favorable  route  for  a  glacial  overflow.  It 
thus  appears  that  both  the  long  systems  named  end  in  deltas  near  the  Little 
Androscoggin  River,  and  are  therefore  a  feature  of  the  later  history  of  the 
Ice  age,  when  the  ice  had  receded  so  far  north  that  this  valley  was  covered 
by  an  arm  of  the  sea  or  by  an  estuary. 

The  length  of  the  system  from  West  Sumner  to  Mechanic  Falls  is 
12  miles. 

BRANCHES    IN    HEBRON    AND    NEAR    WEST    MINOT. 

In  the  northeast  part  of  Hebron  is  a  short  series  of  hillside  kames 
situated  in  the  valley  of  a  small  brook  named  Bicknells  River.  They 
expand  toward  the  bottom  of  the  hill  into  small  terrace-like  plains.  One 
of  these  plains  is  one-eighth  of  a  mile  in  diameter.  It  consists  of  three 
rather  level  terraces,  each  rising  6  to  10  feet  above  the  next  below  it.  The 
gravel  is  but  little  waterworn.  The  general  course  of  the  series  is  south- 
east, and  the  terminal  plains  are  only  about  a  mile  from  the  main  system 
at  East  Hebroii.  It  is  uncertain  whether  this  is  a  local  series  or  whether  it 
was  deposited  by  a  tributary  of  the  main  glacial  river. 

About  three-eighths  of  a  mile  north  of  West  Minot  is  a  series  of  kames 
which  begins  on  the  side  of  a  hill  and  extends  down  the  hill  for  a  short 
fourth  of  a  mile  to  join  the  main  system  in  the  valley. 


under  of  the  esker  extends  northward  up  the  hill  at  the  left. 


/;      HILLSIDE    ESKER    ENDING    IN    GRAVEL  TERRACES^    HEBRON,      LOOKING    NORTH. 


TARMOUTH-GAPE  ELIZABETH  SYSTEM,  215 


HILLSIDE   ESKERS   IN   OXFOBD    COUNTY. 

There  are  several  short  hillside  osars  in  Paris,  Woodstock,  Sumner, 
and  other  hilly  parts  of  Oxford  Count)'.  A  particular  description  of  them 
is  omitted,  since  they  are  so  small  as  not  to  illustrate  the  mode  of  forma- 
tion of  this  class  so  well  as  the  larg-er  deposits  already  described. 

YARMOUTH-CAPE  ELIZABETH   SYSTEM. 

This  is  a  discontinuous  system,  consisting  of  rather  level  plains  up  to 
one-fourth  mile  in  breadth,  and  of  low,  broad  ridges  with  arched  cross  sec- 
tion. The  intervals  between  the  successive  deposits  are  nowhere  more  than 
about  1  mile.  The  gravels  of  this  system  are  usually  found  on  the  tops  of 
low  hills  as  a  rather  thin  cap  overlying  the  till.  The  system  ajDpears  to 
begin  as  a  low  plain  of  gravel  situated  not  far  north  of  Yarmouth  Village. 
In  Yarmouth  Village  it  takes  the  form  of  a  small  plain  of  gravel  and  very 
round  cobbles,  and  then  there  is  a  space  of  about  a  mile  where  the  gravel 
does  not  appear  above  the  marine  clay.  Not  far  north  of  Cumberland 
Post-Ofifice  the  gravel  begins  again,  and  the  intervals  between  the  succes- 
sive ridges  are  then  very  short  for  several  miles.  The  shore  road  (Fal- 
mouth Foreside)  follows  the  course  of  the  gravel  series  as  far  south  as  the 
marine  hospital  near  Portland.  Near  this  point  is  a  small  kame  situated  a 
short  distance  west  of  the  main  system  (near  an  old  rolling  mill  and 
foundry),  which  was  probably  deposited  by  a  small  lateral  tributary.  The 
next  gravel  deposit  of  the  series  is  on  the  top  of  Munjoy  Hill,  in  the 
eastern  part  of  Portland,  as  a  sheet  of  gravel  and  cobbles  capping  a  lentic- 
ular mass  of  till.  A  discontinuous  series  of  gravel  plains  extends  south- 
ward through  Cape  Elizabeth  to  within  a  short  distance  of  the  sea  at 
Bowery  Beach  and  Two  Lights.  I  could  discover  no  sign  of  the  system 
having  at  any  time  extended  south  of  this  point  into  the  sea. 

As  most  of  the  gravels  of  this  series  are  on  hills  less  than  100  feet 
high,  they  were  in  exposed  situations  while  covered  by  the  ocean,  and 
much  of  the  glacial  gravel  has  thereby  been  washed  away  from  the  top  of 
the  ridges,  often  being  spread  over  the  adjacent  fossiliferous  marine  clays. 
Although  these  plains  externally  resemble  delta-plains  in  several  of  their 
features,  yet  the  original  structure  has  so  far  been  modified  on  the  surface 
by  the  sea  that  it  is  unsafe  to  assert  that  the  glacial  gravel  was  originally 


216  GLACIAL  GEAVELS  OF  MAHSTE. 

deposited  by  g-lacial  streams  in  tlie  sea  over  the  marine  clays.  This  can  be 
established  only  by  excavations  reaching  below  the  beach  gravels. 

In  Portland  and  Cape  Elizabeth  the  gravels  of  this  system  are  suspi- 
ciously near  those  of  the  great  Androscoggin  Lakes-Portland  system.  No 
connection  is  yet  proven  between  them,  and  they  are  therefore  classified  as 
distinct  systems.  The  stones  of  this  series  are  in  general  well  rounded, 
though  not  so  much  worn  as  in  many  of  the  longer  systems. 

The  length  of  the  system  is  18  miles. 

ANDROSCOGGIN   LAKES-PORTLAND    SYSTEM. 

This  is  a  large  and  important  discontinuous  system  of  peculiar  type 
and  affording  many  interesting  problems  for  investigation.  For  convenience 
it  will  be  referred  to  as  the  Portland  system. 

The  course  of  the  Androscoggin  River  is  circuitous.  Its  head  waters 
flow  west  into  New  Hampshire,  and  this  part  of  its  valley  is  a  gently  roll- 
ing plain  from  5  to  20  miles  wide.  In  this  plain  is  situated  a  series  of  large 
lakes,  which  may  be  termed  the  Androscoggin  Lakes.  From  Gorham,  New 
Hampshire,  the  river  turns  eastward  into  Maine  again,  and  this  part  of  its 
valley  is  bordered  on  each  side  b}'  high  hills,  which  thus  separate  it  from 
the  valley  of  the  upper  Andi-oscoggin  as  well  as  from  the  valleys  of  Crooked 
River,  the  Little  Androscoggin,  and  other  streams  flowing  southward.  From 
the  region  of  the  Androscoggin  Lakes  several  low  passes  lead  through  the 
high  hills,  one  southeastward  from  Umbagog  Lake  along  the  valley  of  the 
west  branch  of  the  Ellis  River,  and  another  from  Lake  Molechunkemuuk 
southward  down  the  Swift  River.  I  have  not  explored  these  passes.  The 
valleys  of  both  the  streams  just  mentioned  contain  much  alluviuin,  which 
may  wholly  or  in  part  be  an  osar-plain  or  frontal  plain.  A  third  pass  leads 
from  Rangely  Lake  southeastward  down  the  valley  of  Sandy  River.  The 
highest  part  of  the  pass  is  205  feet  by  aneroid  above  Rangely  Lake.  I 
could  find  no  glacial  gi-avel  along  this  pass.  The  lowest  of  all  the  passes 
leads  from  Lake  Welokennebacook  southward  along  Black  Brook  to 
Andover.     This  I  will  name  the  Black  Brook  Pass. 

An  interrupted  gravel  ridge  begins  on  the  west  shore  of  Lake  Moose- 
lookmeguntic  and  follows  that  shore  to  the  outlet  of  the  lake  (here  running 
east  and  west),  when  it  crosses  to  the  south  shore  and  thence  follows  the 
east  shore  of  Lake  Welokennebacook  for  some  miles,  when  it  appears  to 


ANDROSCOGGIN^  LAKESPOETLAND  SYSTEM.  217 

cross  the  lake  obliquely — at  least  the  ridge  soon  appears  on  the  western 
shore  and  continues  thvis  to  the  south  end  of  the  lake,  where  it  forms  a 
prominent  two-sided  ridge.  The  region  lying  south  and  southeast  of  the 
lake  is  so  low  that  only  a  few  feet  of  digging  would  be  required  to  drain 
the  lake  southeastward  down  Black  Brook.  I  am  informed  that  in  time 
past  it  has  repeatedly  been  proposed  to  cut  a  canal  at  this  place  in  order  to 
use  the  water  for  lumbering  purposes  on  Black  Brook  and  the  Ellis  River. 
One  branch  of  Black  Brook  takes  its  rise  within  a  half  mile  of  the  foot  of 
the  lake.  The  osar  continues  southeastward  along  the  broad  and  level  val- 
ley of  Black  Brook  for  about  3  miles,  sometimes  broadening  into  a  plain 
resembling  an  osar-plain  in  appearance.  It  then  enters  a  narrow  V-shaped 
pass  where  the  hills  rise  steeply,  almost  precipitously,  on  each  side  uj)  to 
near  1,000  feet.  The  glacial  river  flowed  through  this  pass,  but  in  its  nar- 
row part  I  saw  no  glacial  gravel  for  a  short  distance.  It  can  hardly  be 
expected  that  any  but  the  larger  stones  and  bowlders  would  be  left  by  the 
stream  in  the  narrow  goi'ge,  and  if  there  were  any  such  they  have  been 
covered  out  of  sight  by  ddbris  that  has  fallen  from  the  high  cliffs.  South 
of  the  narrow  pass  Black  Brook  has  for  several  miles  a  fall  of  50  feet  or 
more  per  mile,  and  here  most  of  the  gravel  was  swept  away  by  the  force  of 
the  glacial  river.  Approaching  Andover  the  slopes  become  gentle,  and  then 
for  3  or  4  miles  the  valley  is  coA^ered  with  a  hummocky  plain  which  soon 
becomes  nearly  horizontally  stratified.  This  plain  is  composed  of  coarse 
gravel,  cobbles,  etc.,  at  the  north,  and  passes  b)"  degrees  into  sand  at  the 
south.  It  fills  the  valley  from  one  side  to  the  other  and  is  of  varying  breadth 
up  to  nearly  a  mile.  The  valley  of  the  Ellis  River  in  Andover  forms  a 
broad  valley  or  mountain  cirque  several  miles  in  diameter,  surrounded  on 
all  sides  by  high  hills,  except  on  the  south.  Into  this  rather  level  plain 
pour  the  Black  and  Sawyer  brooks,  also  the  east  and  west  branches  of  the 
Ellis  River,  all  uniting  not  far  south  of  Andover  to  form  the  main  Ellis 
River.  Sedimentary  plains  of  gravel,  sand,  and  silt  extend  up  all  these  val- 
leys for  a  mile  or  more.  Part  of  these  i^lains  must  have  been  brought 
down  by  these  streams  as  fluviatile  alluvium,  yet  the  alluvium  is  so  abun- 
dant near  the  mouth  of  Black  Brook  as  to  suggest  the  theory  that  the  gla- 
cial river  here  flowed  into  a  lake  which  extended  up  the  tributary  valleys. 
The  cause  of  such  a  lake  will  be  discussed  presently. 

The  valley  of  the  Ellis  River  narrows  near  South  Andover,  and  from 


218  GLACIAL  GRAVELS  OF  MAINE. 

there  to  Rumford  is  from  one-fourth  to  oue-hah'  of  a  mile  wide.  It  is  a 
U-shaped  valley  bordered  by  high  steep  hills.  The  fall  of  the  stream  per 
mile  is  very  small.  A  plain  of  well-rounded  g-lacial  gravel  is  found  in  the 
valley  all  the  way  from  South  Andover  to  Rumford  Point.  For  several 
miles  it  lies  as  a  level  osar-plain  on  the  east  side  of  the  valley,  but  for  2 
miles  north  of  Rumford  Point  it  is  on  the  west  side  and  takes  the  form  of  a 
plexus  of  reticulated  ridges  inclosing  kettleholes  and  a  lakelet.  The  fact 
that  this  gravel  plain  does  not  extend  across  the  whole  valley  is  proof  that 
the  gravel  is  not  valley  diift  but  is  of  glacial  origin.  Along  with  the 
gravel  are  many  cobbles  and  well-rounded  bowlderets,  and  the  slope  of 
the  Ellis  River  is  here  so  gentle  that  it  is  impossible  to  accept  such  coarse, 
well-rounded  matter  as  ordinary  stream  wash.  The  portion  of  the  valley 
not  occupied  by  the  gravel  plain  is  covered  to  a,  considerable  depth  with 
silt  and  clay.  The  base  of  the  gravel  plain  appears  to  underlie  the  clay, 
but  in  places  along  the  margin  of  the  plain  the  gravel  can  be  seen  to  over- 
lie the  clay.  The  great  breadth  of  the  level  portion  of  the  Ellis  River 
Valley  as  compared  Avitli  the  drainage  basin  makes  it  certain  that  the  fluvi- 
atile  drift  would  be  fine  and  the  river  currents  comparatively  gentle,  even 
in  time  of  flood.  This  makes  it  more  probable  that  the  deposition  of  the 
gravel  overlying  the  clay  took  place  in  a  broadened  osar  channel  than  that 
it  was  the  work  of  the  Ellis  River  after  the  melting  of  the  ice. 

For  about  3  miles  from  Rumford  Point  to  the  mouth  of  the  Concord 
River  there  are  occasional  low  ridges  and  hummocks  of  gravel  on  the  west 
side  of  the  Androscoggin  River.  They  rise  out  of  a  low  terrace  of  erosion 
and  externall)^  appear  like  uneroded  portions  of  the  plain  of  valle}'  drift 
which  originally  must  here  have  bordered  the  Androscoggin.  But  exam- 
ination shows  that  they  are  composed  of  gravel,  cobbles,  and  even  bowl- 
(Jerets — ^much  coarser  matter  than  is  contained  in  the  alluvium  of  this  part 
of  the  Androscoggin  Valle}'.  They  are  therefore  glacial  gravel.  It  is  thus 
proved  that  the  course  of  the  glacial  river  crossed  the  Androscoggin  River 
at  Rumford  Point.  If  the  osar-plain  was  originally  deposited  continuously, 
it  has  since  been  eroded  by  the  river.  This  must  have  happened  since  the 
Valley  Drift  period,  for  the  upper  alluvial  terraces  of  the  valley  for  many 
miles  below  this  point  do  not  contain  gravel  similar  to  that  of  the  osar- 
plain.  For  a  short  distance  north  of  the  mouth  of  Concord  River  a  two- 
sided  ridge   of    well-rounded  gravel    and    cobbles    lies    parallel  with  the 


ANDKOSCOGGIN  LAKES  POETLAND  SYSTEM.         219 

Androscoggin  River,  which  here  is  flowing  southeastward.  The  gravel 
soon  turns  southwest  and  ascends  the  valley  of  the  west  branch  of  the 
Concord  River  through  Milton  and  Bethel  to  the  top  of  the  divide  near 
North  Woodstock,  which  is  fully  125  feet  above  Rumford  Point,  and  per- 
haps as  much  as  140  feet.  From  the  Andi'oscoggin  River  to  North  Wood- 
stock this  valley  affords  an  instructive  study.  The  average  slope  is  not 
far  from  25  feet  per  mile.  The  bottom  of  the  valle}^  was  once  occupied 
by  an  alluvial  plain  from  one-eiglith  to  near  one-half  of  a  mile  in  breadth. 
The  osar  ridge  near  the  mouth  of  the  Concord  is  lost  in  the  plain  of  finer 
sediments  soon  after  it  leaves  the  Androscoggin  River.  South  of  this  point 
a  ridge  is  found  along  the  axis  of  the  valley.  It  is  from  10  to  60  feet  in 
height,  and  is  localh'-  known  as  the  "  Whalesback."  Both  sides  of  the  valley 
are  bordered  by  terraces  liaving  nearly  the  same  height  as  the  central  ridge, 
but  composed  of  somewhat  finer  drift.  Near  the  Androscoggin  River  the 
material  is  sand.  Going  southward,  it  becomes  coarser  until,  at  North 
Woodstock,  we  find  only  coarse  gravel,  cobbles,  and  bowlderets.  Both  the 
central  ridge  and  the  lateral  terraces  are  usually  bordered  by  rather  steep 
banks.  They  are  simply  uneroded  portions  of  the  original  plain  which 
extended  across  the  valley.  Two  valle5^s  of  erosion  have  been  formed,  one 
on  each  side  of  the  central  ridge.  These  erosion  valleys,  where  observed, 
do  not  cut  clown  to  the  till,  hence  the  osar-plain  must  have  been  originally 
of  great  depth.  The  valley  is  only  about  8  miles  long,  and  the  small  brook 
that  flows  in  it  does  not  receive  any  lai-ge  tributaries.  It  is  quite  too 
small  to  have  deposited,  even  in  the  highest  floods,  such  a  gravel  plain  as 
once  filled  the  valley.  Indeed,  at  first  it  seemed  to  me  surprising  that  it 
could  have  eroded  the  two  large  valleys  on  each  side  of  the  "Whalesback." 
It  was  not  until  1  had  studied  the  remarkable  erosive  power  of  boiling 
springs  that  I  could  assign  any  physical  cause  for  so  great  an  erosion  in  so 
short  a  valley. 

The  alluvial  terraces  of  the  Androscoggin  Valley  rise  from  30  to  50 
feet  above  the  river  at  the  mouth  of  the  Concord.  The  Androscoggin  at  the 
time  it  stood  at  its  highest  level  must  have  backed  up  the  valley  of  the 
Concord  for  2  miles  or  more,  and  would  fill  that  valley  with  more  or  less 
river  alluvium.  At  North  Woodstock  the  gravel  rises  70  or  more  feet  above 
the  highest  terrace  of  the  Androscoggin  at  Rumford.  It  is  thus  proved 
conclusively  that  the   gravel   along  the   North  Woodstock  Pass  was  not 


220  GLACIAL  GRAVELS  OF  MAINE, 

deposited  by  an  overflow  of  the  Androscoggin  River  after  the  melting  of 
the  ice.  Only  an  ice  dam  at  Riimford  could  cause  an  overflow  up  the 
valley  of  the  west  branch  of  the  Concord  and  over  the  col  at  North 
Woodstock. 

The  following  is  the  probable  history  of  this  interesting  valley:  First, 
a  glacial  river  flowed  southwestward  through  the  North  Woodstock  Pass  in 
a  narrow  channel  along  the  axis  of  the  jiass.  This  was  bordered  on  each 
side  by  ice  walls,  and  in  the  channel  was  deposited  an  osar-ridge.  Subse- 
quently this  channel  gradually  broadened,  and  in  the  broad  channel  was 
deposited  an  osar-plain.  At  length  a  time  came  when  the  channel  extended 
from  side  to  side  of  the  valley,  and  the  osar-plain  thus  came  to  resemble  a 
plain  of  valley  drift  in  its  external  form.  The  broader  the  channel  became 
the  less  rapid,  on  the  average,  was  the  glacial  river  and  the  finer  were  the 
sediments  deposited  by  it.  The  erosion  of  the  plain  has  proceeded  more 
rapidly  in  the  medium  gravel  than  in  the  very  coarse  gravel  of  the  central 
part  of  the  valley  or  in  the  finer  sand  and  gravel  at  the  margins.  Now  a 
dam  of  125  feet  at  North  Woodstock  would  flood  back  the  water  in  the 
broad  osar  channel  for  many  miles  up  the  valley  of  the  Ellis  River.  If 
the  channel  was  open  on  the  top  to  the  air,  or  for  any  reason  the  broad 
osar  river  was  not  confined  within  the  ice  under  high  hydraulic  pressure, 
the  dam  would  cause  the  glacial  river  to  form  practically  a  lake  one-eighth 
to  one-half  mile  wide,  extending  from  North  Woodstock  to  Andover,  where 
it  would  be  at  least  50  feet  deep.  The  glacial  river  pouring  from  the  north 
down  Black  Brook  would  deposit  in  this  dammed  osar-plain  channel  or 
back-water  lake  the  plains  near  Andover  Village  which  so  much  resemble 
lake  deltas.  In  this  long  reach  of  quiet  water  would  be  deposited  the 
fine  clays  of  the  Ellis  Valley  that  border  the  narrower  osar-plain.  The 
osar-plain  of  the  Ellis  Valley  had  been  deposited  in  still  earlier  times  when 
the  channel  of  the  glacial  river  was  not  so  Inroad  as  that  of  the  later  osar 
border  clay.  It  is  also  possible  that  the  sedimentary  drift  near  Andover  is 
in  part  frontal  matter. 

The  highest  part  of  this  pass  is  a  short  distance  north  of  North  Wood- 
stock. Here  a  small  brook  takes  its  origin  and  flows  southward  along  a 
gentle  slope  to  Bryants  Pond.  The  osar-plain  continues  in  this  valley  and 
the  material  becomes  coarser,  and  near  Bryants  Pond  contains  very  round 
bowlders  2  and  even  3  feet  in  diameter.     Here  the  plain  becomes  a  plexus 


ANDROSCOGGIN  LAKESPOETLAND  SYSTEM.  221 

of  two  or  three  broad  ridges,  inclosing  one  deep  and  symmetrical  kettlehole, 
besides  several  shallower  basins.  The  gravel  skirts  the  eastern  border  of 
Bryants  Pond  and  then  it  follows  the  valley  of  the  Little  Androscoggin 
River  for  many  miles  southward. 

South  of  Bryants  Pond  we  have  a  very  difficult  problem,  i.  e.,  to 
distinguish  an  osar-plain  from  valley  drift  on  a  southern  slope  where  the 
glacial  river  flowed  in  the  same  direction  as  the  ordinary  river  which  after- 
wards flowed  in  the  valley.  It  thus  becomes  necessary  to  state  the  facts 
from  which  a  conclusion  may  be  drawn. 

1.  The  gravel  plain  which  extends  from  Rumford  to  North  Woodstock, 
and  so  on  to  the  south  end  of  Bryants  Pond,  is,  without  doubt,  of  glacial 
origin.  The  ice  must  have  covered  the  Androscoggin  Valley  or  the  water 
would  not  have  flowed  southward  over  the  divide  at  North  Woodstock. 
No  geological  fact  can  be  more  certain  than  that  a  mighty  glacial  river, 
large  enough  to  assort  and  polish  the  gTavel,  cobbles,  bowlderets,  and 
bowlders  of  a  plain  one-eighth  to  one-half  of  a  mile  wide,  and  that,  too,  on 
an  up  slope  of  25  feet  per  mile,  flowed  southward  over  the  North  Woodstock 
divide  and  thence  to  the  south  end  of  Bryants  Pond.  Such  a  river  as  this 
can  not  disappear  by  accident,  and  a  river  capable  of  doing  so  gi'eat  an 
amount  of  work  on  an  up  slope  would  do  still  more  on  a  down  slope. 

2.  The  osar-plain  borders  Bryants  Pond  for  about  three-fourths  of  a 
mile.  If  the  basin  where  the  pond  now  is  had  been  bare  of  ice  at  the  time 
the  gravel  plain  was  being  deposited,  there  would  be  nothing  to  hinder  the 
gravel  from  spreading  out  in  fan  sha,pe  across  the  whole  valley.  Instead, 
the  gravel  is  confined  to  a  narrow  belt  along  the  east  side  of  the  pond. 
Here  was  a  torrent  swift  enough  to  make  granite  bowdders  3  feet  in  diame- 
ter almost  as  round  as  marbles,  and  depositing  a  gravel  plain  10  to  20  feet 
higher  than  the  present  pond,  strewing  the  margins  of  the  pond  with  steep 
bluffs  of  bowlderets  and  bowlders,  yet  scrupulously  confining  itself  to  the 
eastern  border  of  a  mountain  valley. 

The  only  satisfactory  explanation  of  these  facts  is  that  the  glacial  river 
was  confined  between  ice  walls  and  that  the  area  which  Bryants  Pond  now 
occupies  was  then  covered  with  ice.  True,  in  the  pass  north  of  North 
Woodstock  the  glacial  river  may  at  this  time  have  extended  from  one  side 
of  the  valley  to  the  other,  like  an  ordinary  river,  yet  it  could  not  have 
followed  the  course  it  did  without  the  presence  of  ice  some  miles  to  the 


222  GLACIAL  GRAVELS  OF  MAINE. 

north  ill  the  Androscoggin  Valley  at  Rumford,  and  also  in  the  Little  Andros- 
coggin Valley  at  Bryants  Pond.  Practically  it  was  a  glacial  river  as  far 
soutli  as  the  south  end  of  Bryants  Pond. 

South  of  this  point  the  valley  of  the  Little  Androscoggin  is  bordered 
by  high  hills.  A  plain  of  mixed  sand,  gravel,  cobbles,  and  bowlderets,  with 
some  bowlders,  extends  along  the  valley  to  West  Paris.  This  plain  is  about 
one-fourth  of  a  mile  wide,  and  the  stones  are  all  very  much  rounded,  like 
those  of  the  osar-plain  at  Bryants  Pond.  It  should  be  noted  that  we  are 
near  the  source  of  the  Little  Androscoggin,  which  stream  is  here  only  a 
a  good-sized  brook.  From  Bryants  Pond  to  West  Paris  the  slope  of  the 
stream  averages  about  35  feet  per  mile;  from  West  Paris  to  South  Paris  it 
is  8  or  10  feet;  and  it  is  only  4  or  5  feet  from  that  point  tu  the  mouth  of  the 
river  at  Auburn.  Now,  in  the  White  Mountains,  where  the  slopes  are  100 
or  more  feet  per  mile,  the  stones  in  the  beds  of  the  streams  are  much 
rounded;  but  I  have  nowhere  seen  them  so  rounded  as  those  in  the  valley 
of  the  Little  Androscoggin  from  Bryants  Pond  to  West  Paris.  North  of 
the  place  where  the  osar-plain  enters  the  valley  of  the  Little  Androscoggin 
there  is  no  such  drift  as  the  plain  of  very  round  stones  that  extends  from 
the  foot  of  Bryants  Pond  to  West  Paris.  Even  in  the  highest  late  glacial 
or  postglacial  floods  the  Little  Androscoggin  could  not  at  this  place  be  a 
very  large  stream,  for  we  are  near  its  head  waters.  From  whatever  stand- 
point, then,  we  look  at  the  plain  of  very  round  gravel,  cobbles,  bowlderets, 
and  bowlders  that  extends  from  Bryants  Pond  to  West  Paris,  we  find  neither 
the  size  of  the  stream  nor  the  steepness  of  slope  necessary  to  account  for 
this  plain  as  fluviatile  sediments.  Besides  we  know  that  a  great  glacial 
river  flowed  into  the  north  end  of  this  valley.  The  steep  hills  would  pre- 
vent it  from  getting  out  of  the  valley.  It  must  have  flowed  down  the  valley 
doing  its  characteristic  work.  The  result  was  this  plain,  which  is  thus 
proved  to  be  chiefly  glacial  as  far  as  West  Paris. 

At  West  Paris  the  valley  of  the  Little  Andi-oscoggin  abruptly  broadens 
into  a  triangular  plain  3  or  more  miles  in  breadth.  One  apex  of  the 
triangle  is  at  West  Paris,  another  at  Trap  Corner,  Paris,  and  the  third  at 
Snows  Falls,  where  the  valley  narrows  to  300  feet.  The  west  side  of  this 
triangular  valley  is  bordered  by  a  plain  of  sand,  gravel,  and  well-rounded 
cobbles  which  extends  in  nearly  a  straight  line  from  West  Paris  to  Snows 
Falls.     It  presents  the  external  appearances  of  an  osar-plain.     East  of  this 


ANDROSCOGGIN  LAKES-POETLA^'D  SYSTEM.  223 

western  border  plain  the  broad  valley  is  covered  by  sand,  silt,  and  clay. 
At  Trap  Corner  the  fine  allu^d^^m  extends  for  a  considerable  distance  up 
two  small  tributary  valleys  to  the  same  height  as  the  clay  plain  of  the 
mam  valley  at  that  place.  This  proves  that  most  of  the  broad  valle}'  was 
at  one  time  covered  by  rather  still  water,  approaching  the  condition  of  a  lake, 
and  this  must  have  happened  after  the  melting  of  the  ice  at  that  place.  If 
the  great  glacial  river  that  deposited  the  osar-plain  to  the  north  had  flowed 
into  the  broad  triangular  valley  below  West  Paris  after  the  ice  had  melted, 
it  must  have  filled  up  the  valley  with  a  delta-plain.  Instead,  the  plain  of 
rounded  gravel  and  cobbles  is  confined  to  a  strip  along  the  west  side  of  the 
broad  valley  hardly  more  than  one-fourth  of  a  mile  wide.  It  is  thus  proved 
that  an  osar-plain  was  formed  in  a  broad  glacial  channel  along  the  western 
border  of  the  triang'ular  valley  at  a  time  when  the  rest  of  the  valley  was 
covered  by  ice.  Later,  when  the  ice  over  the  valley  melted,  this  broad  valley 
formed,  for  a  time,  a  lake,  owing  partly  to  the  great  breadth  of  the  valley  at 
this  point  as  compared  with  its  narrowness  at  Snows  Falls,  and  partly  per- 
haps to  the  osar-plain's  acting  as  a  dam  across  the  valley  near  Snows  Falls, 
In  the  northwestern  part  of  this  lake  coarse  sediment  would  be  deposited  by 
the  swollen  river  of  that  time,  consisting  in  part  of  portions  of  the  eroded 
osar-plain,  while  east  and  south  only  the  finer  sediments  would  be  laid 
down.  It  thus  becomes  reasonably  certain  that  the  drift  of  the  broad 
triangular  valley  that  extends  from  West  Paris  to  Snows  Falls  consists 
of  an  osar-plain  more  or  less  covered  by  alluvium  of  fluviatile  and  lake- 
delta  origin. 

Not  far  south  of  Snows  Falls  the  valley  of  the  Little  Androscoggin 
widens  so  that  the  alluvial  plain  has  an  average  breadth  of  about  half  a 
mile.  It  is  finer  in  composition  than  it  is  north  of  Snows  Falls,  sand  and 
gravel  being  most  abundant,  but  it  contains  numerous  pebbles  and  some 
small  cobbles.  For  1  or  2  miles  south  of  the  falls  the  plain  shows  num- 
bers of  low  ridges  and  shallow  kettleholes.  Then  it  becomes  more  level 
on  the  top,  and  soon  a  two-sided  ridge  is  formed  near  the  river  and  extends 
for  about  3  miles  to  South  Paris.  It  is  locally  known  as  the  ' '  Horseback." 
It  has  the  same  height  as  the  rest  of  the  plain,  and  the  material  appeared  to 
be  little  if  any  coarser  than  that  of  the  plain  at  the  sides  of  the  valley. 
The  ridge  is  the  result  of  erosion  of  the  alluvial  plain  on  each  side  of  the 
horseback  to  a  depth  of  10  to  40  feet.     There  must  be  a  reason  why  this 


224  GLACIAL  GRAVELS  OF  MAINE. 

ridge  has  escaped  erosion,  and  if  fresh  exposures  can  be  found  thej  will 
probably  show  a  mass  of  coarse  matter  at  the  bottom  of  the  ridge,  perhaps 
an  osar  with  arched  cross  section.  We  have  already  seen  that  these  erosion 
ridges  are  common  in  the  osar-plains,  as  in  the  valley  of  Martins  Stream 
'between  Livermore  and  North  Tiu-ner,  and  the  whalebacks  in  Rumford, 
Milton,  Bethel,  and  Wo(vIstock.  In  the  last-named  cases  it  is  quite  easy  to 
determine  that  they  are  ridges  of  erosion  carved  out  from  the  original  osar- 
plains.  Here  we  find  that  the  Little  Androscoggin  is  larger  than  the 
streams  flowing  in  the  valleys  just  named.  Did  it  deposit  the  alluvial  plain 
below  Snows  Falls  as  valley  drift!  Its  drainage  basin  above  South  Paris 
covers  only  a  few  townships,  and  even  in  the  Valley  Drift  period  its  flow 
was  small  as  compared  with  that  of  the  Androscoggin  and  Kennebec  rivers, 
yet  it  is  bordered  by  an  alluvial  plain  nearly  as  large  as  theirs  at  the  same 
distance  from  the  shore  of  the  sea  of  that  period.  There  are  in  the  State 
great  numbers  of  streams  having  as  large  di-ainage  basins  as  the  Little 
Androscoggin  above  Soutli  Paris,  yet  having  very  much  smaller  alluvial 
plains.  This  gives  an  antecedent  probability  that  the  alluvium  of  this  val- 
ley is  largely  glacial. 

The  gravel  along  the  center  of  the  valley  below  Snows  Falls  is  well 
rounded,  like  that  of  the  osar-plain  northward.  But  in  many  places  I 
noticed  that  near  the  margin  of  the  alliTvial  plain  the  gravel  was  but  little 
worn,  in  some  cases  the  till  shapes  being  hardly  modified  at  all,  and  the 
drift  was  almost  morainal.  This  marginal  drift  resembles  the  ordinary 
valley  drift  of  streams  having  no  greater  fall  than  the  Little  Androscoggin 
in  Paris,  and  is  just  such  work  as  could  be  expected  of  the  river  after  the 
ice  had  melted,  oi-  at  the  extreme  margin  of  the  broad  channel  of  an  osar- 
plain. 

We  have,  then,  field  evidence  of  distinctively  glacial  gravel  to  within 
4  miles  of  South  Paris,  and  we  know  that  a  great  glacial  river  flowed  south- 
ward in  the  valley.  General  analogy,  as  well  as  the  local  facts,  indicates 
that  the  central  part  of  the  alluvial  plain  of  the  Little  Androscoggin  north 
of  South  Paris  is  an  osar-plain,  deposited  in  a  broad  channel  between  ice 
walls.  Later,  as  the  ice  melted,  the  water  extended  across  the  whole 
valley.  Alluvium  was  then  deposited  mainly  at  the  sides  of  the  osar-plain, 
and  it  was  subjected  to  much  less  attrition  than  were  the  stones  of  the  older 
glacial  gravel.     It  would  naturally  happen  that  after  the  ice  had  all  melted 


ANDEOSCOGGIiS^  LAKES-PORTLAND  SYSTEM.  225 

in  tlie  Little  Androscoggin  Valley  some  would  still  linger  in  the  Andros- 
coggin Valley  farther  to  the  north,  and  therefore  a  flood  of  glacial  waters 
still  continued  to  pour  south  from  Rumford  to  Bryants  Pond,  and  so  on, 
down  the  Little  Androscoggin  Valley.  These  floods  of  muddy  water,  aug- 
mented by  the  local  drainage  of  the  valley,  woiild  wash  away  and  reassert 
the  surface  portions  of  the  previously  deposited  osar-plain,  and  also  carry 
along  its  burden  of  di'ift  washed  down  from  the  freshly  exposed  hills.  In 
this  way  it  might  happen  that  what  might  be  a  glacial  river  toward  the 
north  could  be  considered  an  ordinary  river  farther  south,  where  it  flowed 
tinvexed  by  ice  to  the  sea.  A  considerable  portion  of  the  alluvial  drift  of 
this  valley  is  undoubtedly  a  valley  delta  of  frontal  glacial  sediment, 
brought  down  by  glacial  streams  and  poured  out  into  the  open  valley,  like 
the  sediments  that  gather  in  the  valleys  below  the  Alpine  glaciers,  or  like 
the  great  plains  of  water- washed  matter  that  extend  south  from  the  terminal 
moraines  of  the  continental  glaciei'. 

South  of  the  South  Paris  and  Norway  villages  the  valley  of  the  Little 
Androscoggin  rapidly  widens.  By  gradual  transition  the  sedimentary  plain 
becomes  finer,  being  composed  of  a  lower  layer  of  silty  clay  overlain  b}^ 
sand  and  fine  gravel.  The  upper  sands  have  been  extensively  eroded, 
largely  by  boiling  springs.  At  Oxford  Village  the  plain  is  about  2  miles 
wide  and  the  upper  stratum  consists  of  fine  sand.  The  Little  Androscoggin 
here  turns  east.  All  the  way  to  Auburn  its  valley  is  covered  by  deep  clays 
with  some  overlying  sand.  It  is  uncertain  how  far  up  the  valley  tide 
water  extended  above  Auburn.  It  is  certain  that  a  broad  stream  or  body 
of  water  at  one  time  covered  the  valley  all  the  way  from  Norway  to 
Auburn,  and  the  lower  (eastern)  portion  was  certainly  salt  water.  Into 
this  body  of  water  poured,  not  only  the  local  drainage,  but  also  for  a  time 
the  glacial  waters  from  the  upper  Androscoggin  Valley  which  then  flowed 
south  from  Rumford  past  Bryants  Pond.  The  large  amount  of  water  that 
must  at  one  time  have  occupied  this  valley  is  well  shown  by  the  broad 
extent  of  sedimentary  plains  in  Oxford.  Two  lines  of  clays,  overlain  by 
sand,  pass  out  from  the  main  valley  and  rejoin  it  again  several  miles  to  the 
south  and  east.  The  more  eastern  of  these  outlying  plains  follows  the 
valley  along  which  the  Grand  Trunk  Railway  is  built.  The  other  plain 
passes  around  the  west  side  of  a  hill  lying  northwest  of  Oxford  Village  and 
•comes  to  the  shore  of  Thompsons  Pond  about  2  miles  west  of  the  village. 

MON  xxxiv 15 


226  GLACIAL  GRAVELS  OF  MAINE. 

At  the  shore  of  the  pond  it  forms  a  bluif  rising  8  or  10  feet  above  the 
water.  At  the  narrowest  jAace  this  plain  is  about  one-eighth  of  a  mile 
wide,  and  a  large  amount  of  water  was  required  in  order  to  form  it.  If 
the  ice  in  the  basin  of  the  pond  was  all  melted  at  the  time  of  the  deposi- 
tion of  this  plain,  the  whole  pond  must  have  stood  at  least  8  feet  above  its 
present  level,  and  a  delta  ought  to  spread  out  in  fan  shape  from  the  mouth 
of  the  inflowing  stream.  Now  from  this  point  to  Oxford  Village  the  pond 
is  bordered  by  a  clay  plain,  and  a  sedimentary  plain  nearly  filled  up  the 
lake,  which  was  flooded  with  water  by  the  building  of  the  dam  at  Oxford. 
But  south  of  here  no  sand  or  clay  borders  the  lake,  except  a  little  near  the 
mouths  of  the  streams — certainly  no  such  sheet  as  could  be  expected  if  a 
large  river  flowed  into  the  pond  2  miles  from  its  outlet  and  at  a  time  when 
it  stood  8  feet  or  more  above  its  present  level.  At  this  time  most  of  the 
basin  of  Thompsons  Pond  must  have  been  covered  by  ice.  Thus  the  sedi- 
mentary^ plains  of  Oxford  appear  in  part  to  have  been  deposited  in  broad 
channels  bordered  by  ice,  and  give  good  ground  for  suspecting  that  these 
broad  channels  practically  formed  a  series  of  glacial  lakes  in  which  a  part 
of  these  fine  sediments  were  deposited.  Subsequently  the  ice  melted,  and 
a  body  of  water,  probably  marine,  filled  the  whole  lower  valley  of  the 
Little  Androscoggin.  How  far  this  was  fluviatile,  -estuarine,  or  marine  is 
somewhat  uncertain,  and  the  hypothesis  is  suggested  that  these  broad  sheets 
were,  in  part  at  least,  bordered  by  ice. 

From  Oxford  Village  a  broad,  low,  plain-like  valley  (known  as  Rabbit 
Valley)  extends  southeastward  to  Poland  Post-Oifice.  About  a  mile  from 
the  Little  Andi-oscoggin  a  ridge  bordered  by  ravines  of  erosion  is  found 
in  the  midst  of  the  plain  of  sedimentary  clay  and  sand  which  here  covers 
the  valley.  Farther  south  what  appears  to  be  a  continuation  of  this  ridge 
rises  higher  than  the  plain  of  fine  sediment,  and  soon  crosses  a  pond, 
which  nearlv  divides  it  into  two  separate  lakes.  Whatever  be  the  char- 
acter of  the  erosion  ridge  farther  north,  this  ridge  at  the  pond  is  distinctly 
an  osar.  Within  2  or  3  miles  the  ridge  is  lost  in  a  rather  level  plain  of 
sand,  gravel,  cobbles,  and  bowlderets,  which  for  several  miles  is  from 
one-fourth  to  one-half  of  a  mile  in  breadth.  The  unmistakable  glacial 
origin  of  this  osar-plain  makes  it  appear  possible,  perhaps  probable,  that 
the  rather  horizontally  stratified  plain  of  clay  and  sand  which  borders  the 
■  ridge  toward   Oxford  Village  was  laid   down  in  a  broad   channel  within 


ANDKOSCOGGIN  LAKESPORTLAIN^D  SYSTEM.  227 

ice  walls,  so  bi'oad  as  to  apj)roacli  tlie  character  of  a  glacial  lake.  In  the 
valley  of  Range  Stream,  not  far  north  of  Poland  Post-Office,  the  osar-plain 
broadens  somewhat,  and  becomes  finer  toward  the  north  and  east,  passing 
from  gravel  into  sand,  and  finally  into  a  clay  plain,  which  extends  north- 
eastward and  at  Mechanic  Falls  joins  the  broad  plain  of  clay  covering 
the  Little  Androscoggin  Valley.  Here,  then,  is  a  delta-plain  v/here  the 
glacial  river  at  one  time  flowed  into  the  broad  body  of  water  which 
occupied  the  valley  of  the  Little  Andi'oscoggin  after  the  ice  had  melted 
to  this  point  but  still  remained  at  Oxford. 

Approaching  Poland  Post-Office,  the  gravel  becomes  coarser  for  about 
2  miles  along  the  north  side  of  the  Lower  Range  Pond.  Here  are  great 
numbers  of  very  round  cobbles,  bowlderets,  and  some  bowlders.  Then 
the  gravel  becomes  finer  toward  the  southeast,  and  in  the  valley  of  the 
Worthley  Brook  consists  of  a  rather  thin  plain  of  sand,  which  has  been 
much  eroded  by  the  stream. 

A  series  of  hills  borders  on  the  south  the  valleys  of  the  Androscoggin 
and  Little  Androscoggin  from  Brunswick  to  Oxford.  Four  low  passes 
penetrate  these  hills.  One  leads  from  Diu'ham  south  through  Pownal, 
one  past  Danville  Junction,  a  third  lies  south  from  Oxford  along  Thompson 
Pond,  and  the  fourth  is  in  the  eastern  part  of  Poland,  leading  along  the 
eastern  base  of  the  high  granitic  hills  on  which  the  Poland  Spring  Hotel 
and  the  Shaker  Village  are  situated.  The  osar-plain  turns  south  along 
the  valley  of  Worthley  Brook  and  penetrates  the  last-named  pass.  It  is 
here  composed  of  rather  fine  drift,  and  is  somewhat  interrupted  in  the 
jaws  of  the  pass.  Soon  after  entering  New  Gloucester  the  system  expands 
into  plains  from  1  to  3  miles  wide,  which  extend  southward  nearly  to 
Gray  Village.  The  western  portion  of  this  large  plain  shows  a  rolling 
surface  and  much  coarse  matter  (cobbles,  bowlderets,  and  bowlders). 
Toward  the  east  and  south  the  surface  is  more  level  (except  where  there 
are  sand  dunes)  and  the  material  is  finer,  passing  at  last  into  fine  sand. 
In  the  midst  of  the  sedimentary  plain  are  several  hills  covered  with  till. 

It  will  be  seen  that  the  eastern  portions  of  the  great  plain  of  New 
Gloucester  and  Gray  present  the  characters  of  a  delta.  Their  relations  to 
the  marine  clays  are  significant.  Two  bays  of  the  sea  once  united  at  these 
plains.  A  line  of  marine  clays  extends  up  the  valley  of  the  Presumpscot 
River  to  Windham,  and  thence  northeastward  up  the  broad  valley  of  Pleasant 


228  GLACIAL  GRAVELS  OF  MAINE. 

Eiver  past  Gray  Village  to  North  Gray.  At  the  same  time  a  bay  10  to 
20  miles  wide  covered  the  lower  valley  of  Royal  River  and  extended  as 
far  north  as  Danville  Junction.  It  joined  the  first-named  arm  of  the  sea  at 
North  Gray.  Thus  a  large  part  of  Cumberland  and  Gray  at  that  time 
formed  an  island,  separated  from  the  mainland  by  a  sheet  of  water  1  to  5 
miles  wide  in  northern  Gray  and  in  New  Gloucester.  The  southeastern  por- 
tion of  the  great  delta-plain  of  New  Gloucester  and  Gray  passes  gradually 
into  clay  about  1 J  miles  north  of  North  Gray.  The  western  portion,  which 
partly  presents  the  external  features  of  an  osar-plain,  partly  those  of  reticii- 
lated  kames,  extends  southward  to  within  tlu-ee-fourths  of  a  mile  of  Gray 
Village.  The  southern  portion  is  a  plain  of  gravel,  with  cobbles  and  some 
bowlderets,  from  one-fom-th  to  three-fourths  of  a  mile  wide.  It  ends  in  a 
steep  bank  and  is  covered  at  its  base  by  the  sedimentary  clay.  The  coarse- 
ness of  the  matter  composing  this  plain  proves  that  it  was  not  deposited  in 
the  open  sea  far  beyond  the  ice  front. 

The  late  glacial  history  of  this  region  must  be  about  as  follows :  First, 
a  broad  plain  of  coarse  gravel,  etc.,  was  deposited  within  an  ice  channel  or 
series  of  channels  along  the  Avestern  side  of  the  great  plains.  Near  Dry 
Mills,  in  the  northern  part  of  Gray,  this  plain  of  coarse  matter  does  not 
extend  back  to  the  hills,  but  ends  on  the  west  in  a  rather  steep  bank.  It  also 
forms  the  barrier  which  has  dammed  back  the  waters  of  Dry  Mills  Pond. 

Subsequently  the  ice  melted,  and  the  sea  advanced  so  that  the  glacial 
river  formed  a  marine  delta  east  of  the  original  osar-plain.  This  is  the 
delta  not  far  north  of  North  Gray.  Still  later  the  sea  advanced  up  the 
valley  of  the  west  branch  of  Royal  River,  and  the  glacial  river  flowed 
into  the  sea  in  this  valley  not  far  east  of  Sabbathday  Pond  in  New 
Gloucester. 

South  of  the  great  plains  of  New  Gloucester  and  Gray  there  are  two 
discontinuous  series.  They  are  provisionall}^  classified  as  delta  branches 
of  one  system,  though  it  is  difficult  to  determine  whether  they  were 
contemporaneous. 

The  first  of  the  western  series  is  the  level  plain  on  which  Gray  Village 
is  situated.  It  is  separated  from  the  more  western  plain  above  described 
by  an  interval  of  more  than  a  mile  of  marine  clay.  On  the  north  bowlderets 
and  cobbles  abound,  but  the  material  grows  finer  toward  the  south,  and 
the  sand  plain   ends  in  marine  clay  within  about  three-fourths  of  a  mile. 


ANDROSCOGGIN  LAKES-POETLAND  SYSTEM.  229 

The  transition  is  quite  abrupt,  and  while  the  plain  is  a  delta,  it  is  uncertain 
whether  it  was  deposited  in  the  sea  or  in  a  glacial  lake.  The  sedimentary- 
clay  continues  for  about  a  mile  south  of  Gray  Village,  and  no  gravel 
appears  above  the  clay  for  about  that  distance.  Then  in  a  low  north-and- 
south  valley  between  high  hills  is  found  a  somewhat  discontinuous  series  of 
broad  hummocks  and  low  ridges,  which  expands  in  the  western  part  of 
Cumberland  and  the  northwestern  part  of  Falmouth  into  a  broad  marine 
delta.  A  tongue  of  this  plain  one-fourth  of  a  mile  or  somewhat  less  in 
breadth  extends  southward  along  the  eastern  base  of  Black  Strap  Mountain 
for  nearly  3  miles  in  Falmoutli.  The  transition  between  this  plain  and 
the  marine  clay  is  so  abrupt  at  the  sides  that  it  must  have  been  deposited 
between  lateral  walls  of  ice.  There  is  a  gradual  transition  to  finer  sedi- 
ments toward  the  south,  and  this  indicates  a  delta  of  some  kind.  The 
glacial  stream  either  poured  into  a  bay  of  the  sea  that  extended  back  into 
the  ice  or  into  a  glacial  lake.  In  the  case  of  this  and  many  similar 
deposits  it  will  require  cross  sections  of  the  deltas  and  the  marine  clays  to 
determine  the  stratigraphical  relations  of  the  coarser  and  finer  sediments. 
Such  sections  are  not  easily  made  without  excavations  for  that  special 
pm-pose,  since  most  of  the  excavations  for  road  gravel,  etc.,  are  purposely 
made  within  the  mass  of  eligible  gravel  and  not  at  the  place  of  transition 
from  the  sands  to  the  clays. 

Black  Strap  Mountain  (Mount  Independence  of  the  Coast  Sm-vey) 
formed  part  of  an  island  when  the  sea  was  expanded.  Along  the  sides  of 
the  "mountain"  are  numbers  of  beaches,  representing  a  considerable  marine 
erosion  of  the  till,  and  these  gravels  have  to  be  distinguished  from  glacial 
gravel.  The  marine  clays  about  its  base  are  deep  and  sometimes  hide 
masses  of  the  glacial  gravel.  This  makes  the  region  a  somewhat  difficult 
one  to  explore.  I  have  not  been  able  with  certainty  to  trace  this  series 
south  of  the  long  narrow  plain  above  described. 

There  is  a  small  delta  at  the  West  Cumberland  Fair-ground.  It  is 
situated  about  a  mile  east  of  the  delta  just  described,  but  does  not  appear 
to  be  connected  with  it.  This  delta-plain  is  of  rounded  fan  shape,  and  on 
the  margins  toward  the  south,  southeast,  and  southwest  the  transition  from 
the  sand  to  the  marine  clay  is  so  gradual  as  to  strongly  indicate  that  it  was 
deposited  in  the  open  sea  by  a  small  glacial  stream  that  probably  was  not 
connected  with  any  other  stream. 


280  GLACIAL  GRAVELS  OF  MAINE. 

We  now  go  back  to  the  great  marine  delta-plains  of  New  Gloucesttj 
and  Gray.  North  Gray  is  situated  in  the  valley  of  a  tributary  of  Royal 
River.  To  the  south  and  west  of  this  valley  is  a  broad-topped  hill,  or 
gently  rolling  plateau,  which  rises  about  75  feet  above  North  Gray  and 
extends  for  several  miles  southward.  A  gravel  plain  about  1  mile  broad 
and  3  miles  long  is  found  on  the  top  of  this  plateau.  It  comes  to  the 
eastern  brow  of  the  hill,  where  it  ends  in  a  rather  steep  slope,  almost  a 
bluff.  Toward  the  north  the  plain  consists  of  broad  reticulated  ridges, 
inclosing  numerous  kettleholes,  one  of  them  being  a  large  basin  70  or  80 
feet  deep.  Bowlderets  and  bowlders  are  here  very  abundant,  and  most 
of  them  are  well  rounded.  Toward  the  south  the  plain  becomes  quite 
level  on  the  top,  and  changes  to  fine  gravel,  and  finally  to  sand.  Beyond 
the  sand  is  marine  clay,  but  I  am  not  certain  whether  the  transition 
between  the  sand  and  the  clay  is  such  as  to  prove  that  this  is  a  delta 
deposited  in  the  sea  or  in  a  glacial  lake.  The  external  appearances  favor 
the  hypothesis  that  this  is  a  marine  delta-plain.  On  the  slopes  of  the  hill 
just  north  of  this  plain  there  are  many  moraine-shaped  ridges  running 
nearly  north  and  south.  It  is  imcertain  whether  they  were  piled  in  their 
present  shapes  by  the  glacier  or  are  erosion  ridges  left  after  the  glacial 
streams  had  washed  away  portions  of  the  till,  leaving  these  as  uneroded 
ridges. 

South  of  this  broad  delta  in  Gray  is  a  level  country  for  3  or  4  miles, 
deeply  covered  by  marine  clay.  Then  the  glacial  gravel  begins  again  as  a 
round  plain  near  one-half  mile  in  diameter,  situated  at  the  north  end  of 
Walnut  Hill,  in  North  Yarmouth.  From  this  point  a  low  level  plain  one- 
eighth  of  a  mile  or  somewhat  more  in  breadth  borders  the  eastern  base  of 
Walnut  Hill,  and  continues  with  perhaps  a  few  short  gaps  to  Cumberland 
Center,  where  it  ends  abruptly.  This  plain  nowhere  rises  more  than  10  to 
25  feet  above  the  marine  clay  which  overlies  its  flanks  and  which  some- 
times covers  the  gravel  out  of  sight.  A  road  is  made  on  top  of  the  gravel 
plain  for  several  miles  in  the  midst  of  a  thickly  settled  country.  Hence 
numerous  wells  have  been  dug  in  the  gravel  plain  or  near  it.  Often  when 
the  surface  shows  onl}^  the  marine  clay,  wells  penetrate  the  clay  into  the 
gravel  and  prove  that  the  plain  is  nearly  continuous  from  the  north  end  of 
Walnut  Hill  to  Cumberland  Center.  In  a  few  cases  (e.  g.,  in  the  western 
part  of  Cumberland  Center)  wells  have  passed  through  the  gi-avel  into  sedi- 


ANDROSCOGGIN  LAKES-PORTLAND  SYSTEM.  231 

mentary  clay.  The  proper  interpretation  of  this  fact  is  uncertain.  The  sea 
waves  may  have  washed  away  the  top  of  the  gravel  ridge  and  strewn  the 
gravel  over  marine  clay  previously  deposited  on  the  flanks  of  the  ridge. 
On  the  other  hand,  the  glacial  rivers  may  have  laid  down  both  the  clay  and 
"the  overlying  coarse  sediments  in  their  present  positions,  either  in  a  broad 
kame  channel  approaching  the  character  of  a  glacial  lake  or  in  a  bay  of  the 
sea  inclosed  between  lateral  walls  of  ice.  But  in  the  last-named  case  the 
plain  ought  to  show  a  transition  into  the  marine  clays  at  the  south  end  of 
-the  plain.  The  abruptness  of  the  transition  favors  the  hypothesis  that  the 
plain  was  deposited  in  a  glacial  lake,  and  that  some  of  the  marginal  clay 
is  not  marine  but  osar  border  clay.  Yet  for  a  mile  north  of  Cumberland 
Center  the  ridge  is  so  situated  that  it  would  be  much  exposed  to  the  waves 
of  the  sea.  Its  surface  is  gently  rounded  in  cross  section,  and  the  above- 
described  phenomena  may  be  due  to  wave  action.  It  will  requu'e  study  of 
many  sections  in  order  to  write  out  the  full  history  of  the  plain  near  Cum- 
"berland  Center. 

Between  Walnut  Hill  station  on  the  Maine  Central  Railroad  and  Cum- 
berland Junction  there  are  two  plains  of  glacial  gravel  lying  one -fourth 
mile  east  of  the  main  ridge  or  plain.  A  projecting  spur  of  the  main  plain 
has  been  extensively  excavated  by  the  railroad  company  a  short  distance 
south  of  Walnut  Hill  station. 

South  of  Cumberland  Center  lies  a  rather  level  region  covered  by 
marine  clay,  and  no  gravel  ajjpears  on  the  surface  for  about  a  mile.  About 
one-fourth  of  a  mile  west  of  Cumberland  Junction,  Maine  Central  Rail- 
road, the  gravel  begins  again  as  a  broad  i-idge,  with  gently  arched  cross 
section,  capping  the  top  of  a  low  north-and-south  hill.  This  ridge  extends 
:southward  to  within  one-fourth  of  a  mile  of  West  Falmouth  station,  it  being 
narrower  and  somewhat  discontinuous  toward  the  south.  At  various  places 
bars  or  tongues  project  obliquely  down  the  eastern  slope  of  the  hill.  South 
of  West  Falmouth  lies  the  plain  of  marine  clay  that  borders  the  Presump- 
scot  River.  No  glacial  gravel  appears  in  this  plain  for  more  than  a  mile. 
A  short  distance  south  of  tlie  river  a  small  gravel  plain  appears  on  the  top 
of  a  low  hill.  Two  other  small  plains,  separated  by  intervals,  bring  us  to 
a  much  larger  gravel  plain,  known  as  Stevens  Plain,  situated  at  Mornills 
Corner  in  the  town  of  Deering.  This  plain  is  somewhat  oblong  in  shape. 
It  is  nearly  a  mile  in  length,  and  about  half  as  broad.     It  is  now  very 


232  GLACIAL  GRAVELS  OF  MAIXE. 

level  on  the  top,  but  it  is  in  a  thickly  settled  region  and  the  surface  may 
not  be  in  its  original  condition.  The  margin  shows  on  nearly  all  sides  a 
steep  slope  outward,  and  the  strata  dip  correspondingly  at  the  exposures 
examined.  The  material  of  the  plain  is  fine  gravel  and  sand  with  some 
thin  layers  of  silty  clay.  At  some  of  the  excavations  examined  the  sedi- 
mentary matter  rested  directly  on  the  solid  rock,  which  has  lost  most  of  the 
glacial  strise  and  is  sand  carved  and  polished  under  the  action  of  the  glacial 
streams.  A  broad  ridge  of  glacial  gravel  begins  a  short  distance  north  of 
Stevens  Plain  and  extends  north  to  the  Presumpscot  River.  Wells  are 
said  to  have  been  dug  80  feet  in  this  ridge  AA'ithout  passing  through  the 
gravel.  Between  this  ridge  and  the  delta-plain  in  West  Cumberland  and 
Falmouth,  before  described  as  lying  along  the  northwestern  base  of  Black 
Strap  Mountain,  there  is  an  interval  of  fully  4  miles.  If  the  Gray- West 
Cumberland  gravel  series  has  any  extension  it  mxist  be  this  ridge  extending 
north  of  Stevens  Plain.     The  local  deposits  of  subangular  gravel  on  the 

south  slopes  of  Black  Strap 

Mountain  are  seabeaches  so 

■^^:•>?ci;^^ii?.io^°:f?=i^35^s^>^^^  far  as  exammed. 


:B:.^^ISi^l®^f  "r^&^pmlgvg  Stevens  Plain  is  prob- 

;^i#Si^v^fer^P^^-^«v^^  ably  a  marine  delta.     The 

Fig.  23.— Landslip  at  Bramhall  Hill,  Portlrmtl.    «,  n,  old  surface,  overlain  +•    T        1   /I"  i' 

with  6  feet  of  well-rounded  gravel  and  cobbles,  with  some  bowlderets.  OUtwarCl  Or  antlClmai  Clip  01 

the  strata  on  all  sides  is  probably  due  in  part  to  the  surf  washing  over 
the  top  of  the  plain.  The  gravel  is  slightly  coarser  on  the  west  side  of 
the  plain. 

The  next  deposit  of  the  system  is  found  as  a  ridge  or  terrace  formed 
against  the  west  end  of  Bramhall  Hill  in  the  western  part  of  Portland. 
The  osar  matter  is  here  rather  coarse,  containing  a  large  proportion  of  cob- 
bles, bowlderets,  and  some  bowlders,  and  most  of  them  are  considerably 
rounded  by  water.  Extensive  landslides  have  taken  place  on  this  hillside. 
Near  the  Boston  and  Maine  transfer  station  a  section  Avas  exposed  a  few 
years  ago  that  showed  an  old  sod  covered  by  several  feet  of  well-rounded 
gravel  and  cobbles.  The  roots  of  grasses  and  other  plants  could  still  be 
distinguished.  The  same  landslips  have  covered  the  fossiliferous  marine 
clays  with  the  glacial  gravel.  The  hills  of  Portland  Avould  be  exposed  to  a 
somewhat  A'iolent  surf  when  the  sea  stood  at  their  IcA-el.  The  Avaves  haA^e 
washed  away  much  of  the  glacial  gravel  from  the  hills  at  each  end  of  the^ 


ASTDKOSCOGGIN  LAKES-PORTLAND  SYSTExM.  235 

city,  and  spread  it  as  beach  gravels  over  the  lower  slopes  of  the  hills,  and 
often  upon  the  fossiliferous  marine  clays.  In  consequence  of  the  landslips 
and  the  overlap  of  the  beach  gravels,  Portland  is  a  difficult  locality  for 
investigating  the  relations  of  the  glacial  gravels  to  the  fossiliferous  marine 
clays. 

South  of  Portland  Harbor  the  connections  of  this  system  are  somewhat 
obscure.  In  Cape  Elizabeth,  near  the  Boston  and  Maine  Railroad,  is  a  sand- 
and-gravel  plain,  not  far  southwest  of  Portland,  and  there  is  another  pretty 
large  plain  near  Oak  Hill  station,  Scarboro.  It  is  probable  that  these  are 
the  connections  of  this  system  rather  than  the  more  eastern  line  of  gravels 
toward  Two  Lights.  Whether  any  of  the  sand  beaches  toward  Old  Orchard 
are  part  of  this  system  is  uncertain. 

The  length  of  the  system,  from  Lake  Mooselookmeguntic  to  Scarboro, 
is  100  miles. 

KENNEBAGO   KAMES. 

These  are  reported  by  Mr.  Huntington,  of  the  New  Hampshire  Geo- 
logical Survey,  as  being  found  in  the  valley  of  the  Kennebago  Stream, 
about  10  miles  north  of  Lake  Mooselookmeguntic.  I  explored  this  river  for 
2  miles  north  of  the  lake,  and  found  an  alluvial  plain,  which  possibly  is  a 
frontal  plain.  The  kames  referred  to  above  are  in  the  proper  position  to  be 
a  branch  of  the  long  Portland  system,  but  more  probably  are  a  local  sys- 
tem of  late  date,  when  the  ice  had  retreated  up  the  valley  for  several  miles 
above  the  lake. 

LOCKES   MILLS   BRANCH. 

The  broad  alluvial  intervale  of  Bethel  extends  nearly  to  South  Bethel. 
At  the  eastern  edge  of  the  alluvial  plain  begins  a  series  of  reticulated  i-idges 
inclosing  kettleholes,  which  extends  eastward  past  Lockes  Mills  in  Green- 
wood. Approaching  the  top  of  the  divide  between  Androscoggin  and 
Little  Androscoggin  waters,  the  gravel  series  becomes  finer  in  composition 
and  expands  into  a  small  sand  plain  at  an  elevation  of  about  75  feet  above 
the  Bethel  intervale.  From  the  top  of  the  divide  eastward  to  Bryants 
Pond  there  is  but  little  alluvium.  A  glacial  stream  from  this  direction 
joined  the  main  system  at  Bryants  Pond  and  left  a  plain  of  gravel  extend- 
ing about  one-fourth  of  a  mile  west  from  the  main  osar-plain.  From  that 
point  to  the  top  of  the  divide  not  far  east  of  Lockes  Mills  I  have  not  been 


234  GLACIAL  GRAVELS  OF  MAINE. 

-able  to  trace  the  gravels.  This  makes  it  proljable  that  not  much  if  any 
overflow  took  place  from  Lockes  Mills  eastward  after  the  ice  had  become 
melted  west  and  northwest  of  Bryants  Pond. 

A  short  line  of  glacial  gravels  comes  from  the  north  and  joins  the 
South  Bethel  series  ]iear  Lockes  Mills.  There  are  some  signs  that  this 
series  extended  northward  across  the  middle  intervale  of  the  Andi'oscoggin 
in  Bethel  as  an  osai'-plain,  and  then  up  the  valley  of  Bear  River  toward 
Umbagog  Lake.  I  have  not  been  able  to  find  time  for  a  careful  explora- 
tion of  the  route,  and  provisionally  mark  this  gravel  series  as  extending 
only  about  a  mile  north  from  Lockes  Mills. 

It  has  already  been  noted  that  there  may  have  been  an  OA^erflow  from 
the  direction  of  Umbagog  Lake  to  Andover,  and  that  possibly  a  branch  of 
the  Portland  system  followed  the  valley  of  the  west  branch  of  the  Ellis 
River. 

GENERAL    NOTE    ON    THE    PORTLAND    SYSTEM. 

Tlu-ee  times  this  system  of  glacial  gravels  goes  up  a  valley  of  natural 
•di-ainage  to  its  source  and  crosses  hills  into  other  valleys,  but  it  does  not 
■cross  hills  higher  than  150  feet.  In  order  to  penetrate  the  high  hills  by  so 
low  passes,  it  makes  some  remarkable  deflections  in  its  course.  At  Oxford 
ihere  was  in  front  of  it  a  very  low  pass  south-sA-ard  (along  Thompson  Pond), 
but  it  took  a  higher  pass  southeastward  through  Poland,  following-  a  course 
more  nearly  parallel  to  the  glacial  striae  than  was  the  other.  The  system 
takes  the  form  of  an  osar  or  osar-plain  for  most  of  the  way  north  of  the 
Gray-New  Gloucester  marine  delta.  South  of  that  point  it  is  constantly 
discontinuous,  i.  e.,  it  consists  of  a  series  of  plains  or  broad  ridges  sepa- 
rated by  intervals  from  a  half  mile  up  to  3  or  4  miles.  In  this  part  of  its 
com'se  the  gravels  appear  on  the  tops  of  low  hills  or  along  the  eastern  bases 
of  such  high  hills  as  Walnut  Hill  and  Black  Strap  Mountain.  The  plain 
at  Oak  Hill  in  Scarboro,  Stevens  Plain  in  Deering,  the  plain  at  West 
■Cumberland  Fair-ground,  and  the  other  plain  west  of  it  in  Cumberland 
and  Falmouth,  also  a  large  part  of  the  Gray-New  Gloucester  ijlains,  I  con- 
sider as  marine  deltas.  The  last  named  are  by  far  the  largest  of  these,  and 
are  situated  at  an  elevation  of  200  to  230  feet.  Several  others  of  these 
plains  are  deltas  of  some  kind,  but  I  am  not  certain  Avliether  they  were 
•deposited  in  the  sea  or  in  glacial  lakes.  Several  of  these  deposits  show 
•some  l^ut  not  all  of  the  characters  of  deltas.     Their  material  is  so  coarse. 


OASCO-WINDHAM  SYSTEM.  235 

even  to  the  edge  of  the  deposit,  as  to  prove  that  they  were  formed  between 
ice  walls  and  not  in  the  open  sea.  The  student  of  the  drift  of  Maine  should 
certainly  explore  this  system,  though  in  many  places  it  is  quite  inaccessible 
and  considerable  time  is  required  to  do  it  justice. 

LOCAL    ESKEE    IN   WESTBROOK. 

A  short  kame  is  situated  on  the  north  side  of  the  Presumpscot  River  a 
short  distance  east  of  Cumberland  Mills. 

CASCO-WINDHAM    SYSTEM. 

Thompson  Pond  extends  from  Oxford  south  tln-ough  Otisfield  and 
Poland  into  Casco.  It  occupies  a  long'  north-and-south  valley,  which  at  the 
north  is  2  or  3  miles  wide,  but  becomes  narrower  in  Casco,  so  that  at 
the  south  end  of  the  pond  it  is  hardly  one-eighth  of  a  mile  wide,  while 
south  of  the  jDond  lies  an  almost  V-shaped  valley,  bordered  by  high 
granitic  hills.  At  the  foot  of  the  pond  the  bases  of  the  bordering'  hills  are 
strewn  with  a  number  of  hummocks  of  till,  also  some  morainal  ridges, 
which  are  somewhat  transverse  to  the  valley.  They  appear  like  moraines 
of  a  local  glacier  occupying  the  basin  of  the  pond.  This  narrow  valley 
terminating  the  much  broader  valley  toward  the  north  would  be  favorable 
for  the  formation  of  moraines  during  the  final  melting  of  the  ice,  on  account 
of  the  great  convergence  of  the  movement  into  so  narrow  a  pass.  In  the 
midst  of  the  valley,  at  the  south  end  of  the  pond,  begins  a  series  of  low 
bars  of  glacial  gravel.  The  stones  have  been  but  little  changed  from  tlieir 
till  shapes,  a  fact  which  proves  this  to  be  near  the  north  end  of  the  system. 
Only  a  small  brook  flows  northward  into  the  lake,  and  there  is  no  way  of 
accounting  for  this  gravel  as  fluviatile  alluvium.  Groing  south  we  find  the 
gravel  becoming  rounder.  A  very  low  divide  separates  the  waters  of 
Thompson  Pond,  flowing  north,  from  those  floAving  south.  The  glacial 
river  flowed  over  this  divide  and  thence  in  a  nearly  straight  line  to  Rattle- 
snake Pond,  Casco.  Not  far  north  of  this  pond  it  flowed  over  a  vertical 
cliff  of  rock  20  feet  high.  The  cliff  faces  south,  and  a  subglacial  river 
flowing  in  that  direction  would  naturally  have  eroded  the  rock  at  the  base 
of  the  cliff  if  it  flowed  over  it  so  as  to  form  a  waterfall,  but  there  is  no  jjot- 
hole  or  visible  channel  of  erosion  in  the  solid  rock.  The  course  of  the 
glacial  river  could  easily  be  traced  at  this  point  by  the  piles  of  rounded 


236  GLACIAL  GEAVELS  OP  MAINE. 

gravel,  cobbles,  and  larger  stones  found  at  short  intervals  in  a  strip  only 
about  100  feet  wide.  The  rock,  where  unweatlaered,  was  very  smooth,  but 
whether  this  was  due  to  water  polish  or  to  the  attrition  of  the  glacier  was 
uncertain.  There  was  little  till  along  the  line  of  the  glacial  stream.  Here, 
then,  was  a  rather  small  glacial  stream  that  eroded  the  till  and  tumbled 
over  a  steep  cliff,  yet  did  not  erode  a  traceable  channel  in  the  solid  rock  or 
form  a  pothole.  The  stones  of  the  glacial  gravel  are  all  very  much 
rounded  here,  and  must  have  been  subjected  to  a  large  amount  of  rolling. 
A  plausible  explanation  of  these  facts  lies  in  the  hypothesis  that  the  stream 
was  for  a  time  occupied  in  eroding  the  till,  and  that  it  ceased  to  flow  soon 
after  the  rock  had  been  laid  bare.  The  gravels  pass  beneath  the  water  at 
the  north  end  of  Rattlesnake  Pond  and  soon  reappear  on  the  western 
shore.  The  glacial  river  followed  this  shore  of  the  pond  all  the  way  to  its 
south  end.  Between  Rattlesnake  and  Panther  ponds  the  glacial  gravel 
takes  the  form  of  an  osar-plain.  The  gravel  reappears  near  the  south  end 
of  Panther  Pond,  and  continues  as  an  osar-plain  to  Raymond  Village. 
Here,  near  where  the  system  crosses  the  outlet  of  Panther  Pond,  there  is 
apparently  a  short  gap  in  the  gravel  plain.  The  plain  soon  begins  again, 
and  continues  its  southwest  course  till  it  reaches  the  shore  of  Sebago  Lake, 
when  it  txu-ns  south  and  follows  the  east  shore  of  the  lake  for  a  half  mile  or 
more.  It  rises  6  to  12  feet  above  the  lake,  and  often  ends  at  the  lake  in  a 
cliff  of  beach  erosion.  In  all  this  part  of  its  course  the  osar-plain  continues 
an  eighth  of  a  mile  in  breadth,  or  in  places  a  little  broader.  There  was 
nothing  to  hinder  an  ordinary  stream  having  a  southwest  course  froiu 
sweeping  its  sediments  out  into  the  lake.  The  fact  that  there  is  no  fan- 
shaped  delta  at  this  point,  though  the  stream  that  deposited  the  osar-plain 
flowed  at  an  elevation  of  several  feet  above  the  lake  and  was  rapid  enough 
to  transport  cobbles  and  bowlderets,  is  conclusive  proof  that  at  the  time  the 
plain  was  being  deposited  the  basin  of  Sebago  Lake  was  covered  by  ice  at 
this  point. 

The  gravel  plain  soon  leaves  the  shore  of  the  lake  and  continues 
southward  over  a  pass  50  to  70  feet  high  to  North  Windham.  In  this  part 
of  its  course  the  system  takes  the  form  of  a  plexus  of  broad  reticulated 
ridges  and  hillocks,  and  it  contains  many  kettleholes  and  hollows  of  all 
sizes  up  to  lake  basins.  Toward  the  south  the  jjlains  spread  out  in  fan 
shape  and  the  ridges  become  lower  and  gradually  coalesce  into  a  rather 


CASOO- WINDHAM  SYSTEM.  ,  237 

level  plain  composed  largely  of  sand  and  fine  gravel,  which  near  North 
Wmdham  is  not  far  from  2  miles  broad.  Sonth  of  this  point  the  gravel 
narrows  so  as  to  form  a  rather  level  plain  about  one-fourth  of  a  mile  wide, 
which  continues  southward  past  Windliam  Hill  to  a  point  about  one-half 
mile  south  of  Windham  Center.  Near  the  south  end  of  this  plain  the 
material  is  very  coarse,  consisting  chiefly  of  cobbles  with  bowlderets  and 
bowlders. 

In  many  places  in  this  system  there  are  great  numbers  of  rounded 
bowlders  2  to  4  feet  in  diameter,  a  fact  which  favors  the  hypothesis  that 
it  was  deposited  by  subglacial  sti-eams. 

South  of  Windham  there  are  several  plain-like  deposits  of  glacial 
gravel  in  Grorham  and  Scarboro  which  are  probably  marine  deltas.  The 
largest  of  these  plains  is  at  Grorham  Village.  They  are  in  the  proper  posi- 
tions to  have  been  formed  by  the  same  glacial  river  that  brought  down 
the  gravels  of  the  Casco- Windham  system.  But  the  country  is  so  level 
that  we  have  no  hills  to  act  as  ba;rriers  to  confine  the  glacial  rivers,  and  the 
intervals  between  the  plains  are  so  long  that  provisionally  I  mark  the 
system  as  ending  in  Windham. 

The  gravels  of  .this  system  form,  wholly  or  in  part,  the  dam  which 
caused  the  formation  of  Little  Sebago  Lake,  in  Windham  and  Gray.  The 
original  outlet  of  this  lake  flowed  west  into  the  Presumpscot  River,  and  its 
bed  shows  only  glacial  gravel  for  some  distance  from  Little  Sebago  Lake. 
An  artificial  channel  has  been  dug  for  the  purpose  of  taking  the  water  of 
the  lake  south  into  the  Pleasant  River,  the  small  stream  flowing  from 
Gray  southwestward  into  the  Presumpscot  in  Windham.  This  channel  is 
dug  wholly  in  the  glacial  gravel. 

The  North  Windham  Plains  pass  by  degrees  into  sand,  and  finally 
into  marine  clay  toward  the  south  and  east.  They  are  marine  delta- 
plains  in  part,  found  in  the  arm  of  the  sea  which  extended  from  Windham 
northward  past  Gray  and  joined  the  bay  that  then  covered  the  valley  of 
Royal  River.  But  perhaps  there  is  a  continuous  plain  of  purely  glacial 
gravel  near  the  axis  of  the  area  which  is  continuous  with  the  Windham 
Center  Plain. 

At  Raymond  Village  the  osar-plain  is  bordered  and  partly  covered  bv 
:sedimentary  clay.  This  is  at  an  elevation  of  about  20  feet  above  Sebago 
Xake.     There  is  no  continuous  sheet  of  clays  at  this  elevation  around  the 


238  GLACIAL  GRAVELS  OF  MAINE. 

lake,  and  this  disproves  the  theory  that  the  lake  or  the  sea  stood  at  this  ele- 
vation. This  clay  is  probably  osar  border  clay  deposited  in  a  very  broad 
channel  within  the  ice  at  a  very  late  period  of  the  Ice  age. 

This  system  lies  in  a  region  where  the  rocks  are  chiefly  granitic  and 
the  till  is  ver}^  abundant.  Although  not  long,  it  contains  a  very  large 
amount  of  gravel. 

GRAY-NORTH    WINDHAM   SERIES. 

On  the  eastern  side  of  Little  Sebago  Lake  is  a  high  range  of  hills 
which  extends  continuously  northward  to  Poland.  At  a  point  about  west 
of  Grray  Village  a  discontinuous  series  of  short  ridges  of  glacial  gravel 
begins  near  the  eastern  base  of  this  high  range.  At  the  north  end  the 
gravel  is  but  little  waterworn,  and  it  is  separated  from  the  Grray-New 
Gloucester  plains  by  a  hill  more  than  100  feet  high.  For  these  reasons  I 
regard  this  series  as  distinct  from  the  Portland  system,  although  the  two 
series  are  only  2  or  3  miles  apart  in  Grray.  This  series  extends  southwest- 
ward,  passing  about  one-fourth  of  a  mile  west  of  West  Gray.  It  soon 
becomes  a  continuous  osar-plain,  and  when  approaching"  North  Windham 
rapidly  broadens  into  a  delta-plain.  Near  North  Windham  it  is  difficult  to 
distinguish  the  gravels  of  this  series  from  those  brought  down  by  the  large 
glacial  river  from  Casco  and  Raymond.  Whether  this  series  should  be  con- 
sidered a  branch  of  the  Casco  system  is  uncertain.  If  the  stream  which 
deposited  it  began  to  flow  in  early  glacial  time,  it  would  natm-ally  flow  into 
the  larger  glacial  river,  but  if,  as  is  more  probable,  it  dates  from  the  very 
last  part  of  the  Ice  age,  then  it  may  have  flowed  into  the  sea  at  North 
Windham  near  where  the  other  glacial  river  also  poured  into  the  sea,  yet 
have  been  distinct  from  it. 

GENERAL   NOTE    ON    THE    GLACIAL   GRAVELS   OF    SOUTHWESTERN  MAINE. 

The  systems  of  glacial  gravels  thu's  far  described  are  not  so  closely 
connected  with  one  another  in  any  part  of  their  courses  but  that  it  is  rela- 
tively easy  to  distinguish  them.  Most  of  the  gravels  remaining  to  be 
described  are  connected  with  one  another  not  only  at  the  great  marine 
delta-plains  which  were  deposited  at  elevations  from  175  to  230  feet  above 
the  sea,  but  also  by  transverse  branches  connecting  the  broad  plains  of 
reticulated  ridges  found  above  230  feet.  Some  of  them  are  also  connected 
by  lateral  branches  at  points  north  of  the  plains  of  reticulated  kames  in 


BASIN  OF  SEBAGO  LAKE.  239 

the  region  of  the  osar -plains.  As  employed  in  this  report,  the  word  "sys- 
tem" denotes  the  gravels  deposited  by  a  single  glacial  river  with  its 
branches,  both  delta  and  tributary.  According  to  this  nomenclature, 
almost  all  of  the  vast  gravel  deposits  of  southwestern  Maine  are  connected 
as  a  single  system.  The  word  "series"  will  therefore  be  used  to  designate 
a  single  line  or  branch  of  this  wonderfully  complex  network.  An  inspec- 
tion of  the  map  will  give  a  far  better  idea  of  these  reticulations  than  a 
verbal  description  could  give.  In  some  cases  it  is  easy  to  determine  which 
way  the  water  flowed  that  formed  the  transverse  lines  of  gravel  connecting- 
the  north-and-south  series,  but  often  this  is  difficult  or  impossible.  Some- 
times the  flow  has  probably  been  alternately  in  opposite  directions. 

NOTE  ON  THE  BASIN  OF  SEBAGO  LAKE. 

Sebago  Lake  is  said  to  have  a  larger  water  surface  than  any  other  of 
the  Maine  lakes.  It  is  interesting  in  many  ways.  It  occupies  a  broad 
north-and-south  valley,  which  is  a  rock  basin  if  the  depth  of  the  lake  is 
correctly  reported  at  400  feet,  or  even  if  it  has  half  that  depth.  One  who 
stands  on  the  high  hills  of  Waterford  and  looks  south  along  the  deep,  almost 
V-shaped  valley  which  reaches  southward  through  Harrison  and  then  broad- 
ens into  the  beautiful  valleys  containing  Long  Pond  and  Sebago  Lake,  will 
see  that  here  are  some  interesting  questions  in  structural  geology.  From 
the  standpoint  of  the  glacialist  the  region  is  no  less  interesting.  Several 
valleys  converge  toward  the  basin  of  Sebago  Lake,  down  which  the  ice 
could  continue  to  flow  long  after  the  general  movement  across  and  over  the 
higher  hills  had  ceased.  From  the  north  the  ice  could  easily  flow  down 
the  valley  of  Long  Pond,  also  down  that  of  the  Crooked  River.  From  the 
northeast  the  ice  could  easily  flow  from  Raymond,  Casco,  and  Thompson 
Pond  along  the  valleys  where  lies  the  Casco- Windham  system  of  glacial 
gravels,  while  a  broad  valley  from  near  South  Bridgton  would  allow  a  flow 
from  the  northwest.  The  valleys  would  in  fact  contain  their  local  glaciers, 
and  these  would  coalesce  in  the  basin  of  the  lake  to  form  a  single  mer  de 
glace,  which,  during  the  final  melting,  would  retreat  less  rapidly  than  the 
ice  in  adjoining  regions  so  situated  that  the  flow  of  the  ice  from  the  north 
was  more  thoroughly  cut  off  by  high  transverse  hills.  There  are  in  Maine 
several  places  where  the  ice  probably  met  the  sea,  and  terminal  moraines 
were  formed  at  the  ice  front.     These  are:  (1)  At  Readfield  Village;   (2)  on 


240  GLACIAL  GRAVELS  OF  MAINE. 

the  southeast  shore  of  Swan  Island,  in  the  Kennebec  Rivei";  (3)  in  the  vil- 
lage of  Sabatisville ;  (4)  near  the  head  of  Little  Kennebec  Bay,  a  few  miles 
south  of  Machias  Village;  (5)  at  Winslows  Mills,  in  Waldoboro.  It  might 
be  expected  that  the  tongue  of  ice  that  filled  the  basin  of  Sebago  Lake 
would  in  like  manner  confront  the  sea,  and,  in  consequence  of  the  abundant 
flow  of  ice  from  the  north,  would  retreat  with  relative  slowness,  a  condition 
favorable  to  the  formation  of  a  terminal  moraine. 

NAPLES-STANDISH   SERIES. 

A  terrace-like  ridge  or  level  plain  of  sand  skirts  the  western  shore  of 
Long  Pond  for  tlu'ee-fourths  of  a  mile  north  of  Naples  Village.  At  this 
point  it  rises  somewhat  more  than  20  feet  above  the  pond,  and  there  is  no 
similar  deposit  on  the  east  side  of  the  pond,  nor  around  the  pond.  The 
terrace  at  Naples  Village  is  at  least  10  feet  deep.  Is  it  an  old  beach,  formed 
at  a  time  when  the  pond  stood  20  or  more  feet  above  its  present  level? 

1.  If  a  terrace  10  feet  deep  could  form  as  a  beach  on  the  west  side  of 
the  pond  and  iu  a  sheltered  situation,  then  similar  beaches  ought  to  be 
found  in  all  the  sheltered  bays  of  the  lake,  especially  on  the  east  side. 
There  are  no  such  beaches  deep  enough  to  be  traceable. 

2.  The  erosion  cliffs  along  the  shores  of  the  pond  at  its  present  level 
are  too  small  to  account  for  a  terrace  of  sand  near  one-eighth  of  a  mile 
wide  and  10  feet  deep.  If  the  Naples  terrace  is  a  beach,  then  a  corre- 
sponding erosion  cliff  or  other  sign  of  the  erosion  ought  to  be  found  around 
the  lake.  There  is  proof  that  the  lake  must  have  formerly  stood  at  a  higher 
level  than  at  present,  but  it  has  left  no  cliffs,  nor  any  places  denuded  of  till, 
nor  any  recognizable  beaches. 

3.  No  stream,  except  mere  brooks  about  a  mile  long  can  ever  have 
flowed  into  Long  Pond  at  Naples  Village.  The  sand  terrace  can  not,  there- 
fore, be  a  delta  brought  by  streams  into  the  lake  at  a  time  when  it  stood  at 
a  higher  level  than  at  present. 

It  thus  appears  that  the  sand  terrace  at  Naples  is  neither  a  beach  nor  a 
lake  delta,  and  the  only  way  to  account  for  it  is  to  assume  that  it  is  an  osar- 
plain.  The  plain  continues  southward  along  the  west  shore  of  Brandy 
Pond  (Bay  of  Naples),  becoming  coarser  toward  the  south;  and  at  the  out- 
let of  this  pond  it  has  become  a  two-sided  ridge  with  arched  stratification. 
At  this  point  there  are  several  outlying  ridges,  somewhat  reticulated,  one 


NAPLES  STANDISH  SEKIES.  241 

of  which  once  formed  a  dam  across  the  Long  Pond  (here  very  narrow)  and 
raised  it  probably  20  or  more  feet  above  its  present  level.  The  outlet  of 
the  pond  has  in  process  of  time  eroded  the  obstructing  ridge  and  lowered 
the  level  of  Long  and  Brandy  ponds.  All  of  these  ridges  at  the  outlet  of 
Brandy  Pond  (Songo  Lock)  are  composed  of  coarse  gi-avel  with  cobbles 
and  bowlderets.  The  distinctively  glacial  origin  of  these  coarse  sediments 
is  an  additional  proof  of  the  glacial  origin  of  the  sand  terrace  at  Naples 
Village,  which  is  connected  by  a  continuous  deposit  of  sand  and  gravel 
with  these  osars.  The  osar-plain  at  Naples  is  remarkable  from  the  fact  that 
it  is  composed  of  such  fine  material  at  its  north  end.  Whether  the  system 
extends  northward  under  Long  Pond  is  uncertain.  There  are  small  deposits 
of  sand  and  rolled  gravel  reported  on  the  shore  of  the  pond  and  on  islands 
in  that  direction,  but  I  now  regard  them  as  probably  being  beach  gravels 
of  the  lake. 

At  Songo  Lock,  at  the  south  end  of  Brandy  Pond,  there  are  a  few 
ridges  that  have  a  northeast-and-southwest  direction.  They  are  arranged 
transversely  across  the  valley,  as  the  moraines  of  a  local  glacier  would  be, 
but  on  the  surface  they  are  composed  of  rounded  gravel,  and  I  consider 
them  probably  kames,  perhaps  deposited  by  a  short  tributary. 

South  of  Songo  Lock  an  osar  extends  nearly  continuously  to  the  north- 
ern shore  of  Sebago  Lake  at  a  point  a  short  distance  west  of  the  mouth  of 
Songo  River,  which  forms  the  mouth  of  Crooked  River.  The  ridge  ends 
in  a  cliff  of  beach  erosion  about  35  feet  high.  Part  of  the  way  south  of 
Songo  Lock  the  ridge  is  flanked  by  outlying  hummocks  and  by  a  rather 
level  plain  resembling-  an  osar-plain  in  external  form. 

The  evidence  is  thus  conclusive  that  a  large  glacial  river  flowed  south 
into .  the  basin  of  Sebago  Lake.  Numerous  credible  witnesses  report  the 
northwest  bay  of  the  lake  as  being  from  250  to  400  feet  deep.  Glacial  gravel 
reappears  at  Sandy  Beach,  on  the  western  shore  of  the  lake,  about  3  miles 
from  where  it  disappears  at  the  north  end  of  the  lake.  A  narrow  plain  of 
glacial  gravel  extends  southward  for  several  miles  along  the  western  shore  of 
the  lake,  soon  expanding  into  extensive  plains  in  Standish.  These  plains  are 
rather  level,  yet  show  some  basins  and  reticulations.  The  glacial  river  must 
have  flowed  across  the  deep  basin  of  the  northwestern  angle  of  the  lake. 
A  tongue  of  these  plains  extends  southeastward  to  the  south  end  of  the  lake, 
where  it  expands  into  a  rounded  plain  more  than  a  mile  in  diameter.  Next 
MON  xxxiv 16 


242  GLACIAL  GRAVELS  OF  MAINE. 

to  the  lake  the  material  of  this  plain  is  very  coarse,  containing  great  numbers 
of  cobbles,  with  bowlderets  and  some  bowlders.  The  surface  is  here  very 
irregular,  and  the  graA^el  consists  of  a  series  of  reticulated  ridges  inclosing 
kettleholes  and  basins  of  various  sizes,  some  of  them  occujaied  by  lakelets 
and  peat  swamps.  The  Maine  Central  Railroad  was  originally  constructed 
across  one  of  the  peat  swamps.  The  peat  soon  sank  under  the  weight  of 
the  roadbed,  showing  that  the  peat  overlay  a  lakelet.  The  chasm  was  then 
filled  up  by  an  embankment  of  gravel,  85  feet  above  the  top  of  the  water, 
which  stood  at  the  same  level  as  the  lake.  A  depression  95  feet  deep  is 
found  on  the  bottom  of  the  lake  a  few  rods  north  of  the  shore  at  the 
south  end  of  the  lake.  It  is  surrounded  on  all  sides  by  much  shallower 
water,  and  is  probably  a  kettlehole.  The  water  at  the  south  end  of  the 
lake  is  from  20  to  40  feet  deep  except  at  this  depression.  No  rock  in 
place  appears  anywhere  near  the  south  end  of  the  lake  nor  along  a  line 
extending-  southeast  from  this  point. 

The  most  probable  interpretation  of  these  facts  is  this:  In  preglacial 
time  the  region  where  Sebago  Lake  now  is  was  di-ained  by  a  valley  which 
extended  from  the  foot  of  the  lake  southeastward  to  the  Presumpscot 
Valley  near  Saccarappa.  In  late  glacial  and  early  postglacial  time  this 
valley  was  filled  by  till,  glacial  gravel,  and  sedimentary  clay  to  a  depth  of 
100  feet  or  more.  After  the  final  melting  of  the  ice  the  water  found  the 
old  drainage  valley  effectually  dammed,  and  it  filled  up  the  basin  till  it 
began  to  overflow  7  miles  northeast  of  the  old  channel  The  Presumpscot 
River  (the  outlet  of  Sebago  Lake)  flows  over  a  rock  bed,  showing  a  constant 
succession  of  rapids  and  '^^^aterfalls  all  the  way  from  Sebago  Lake  to  near 
Saccarappa.  This  indicates  that  it  is  a  recent  channel  for  the  main  stream, 
though  in  preglacial  time  this  valley  was  occupied  by  a  branch  of  the  main 
stream.  Sebago  Lake  would  be  about  100  feet  lower  than  it  is  but  for  the 
plain  of  glacial  gravel  at  its  south  end,  and  would  be  greatly  reduced  in 
size.  Portland  owes  the  convenience  of  its  water  supply  to  this  same  dam 
of  glacial  gravel.^ 

The  plains  of  glacial  gravel  that  border  the  lake  vary  from  10  to  40 
feet  in  depth,  except  at  the  south  end,  where  they  exceed  130  feet.     The 

'Since  the  above  was  written  I  have  discovered  that  the  gravelly  nature  of  the  southern 
boundary  of  Sebago  Lake  attracted  the  attention  of  Prof.  C.  H.  Hitchcock;  see  Preliminary  Eeport 
upon  the  Natural  History  and  Geology  of  the  State  of  Maine,  p.  288,  1861. 


NAPLES  STANDISH  SERIES.  243 

basin  of  the  lake  is  somewhat  triangular,  and  the  ice  would  naturally  con- 
verge toward  the  narrow  end  at  the  south.  The  unusually  deep  mass  of 
glacial  gravel  south  of  the  lake  is  probably  in  part  a  sort  of  terminal 
moraine  formed  at  the  end  of  the  tongue  of  ice  which  occupied  the  basin 
of  the  lake.  A  small  movement  over  the  broad  part  of  the  basin  and  its 
tributary  valleys  would  cause  a  much  larger  flow  at  the  extremity,  where  it 
was  only  a  mile  wide.  This  would  naturally  cause  a  convergence  of  the 
flow  of  the  ice,  and  also  of  the  glacial  rivers  to  this  place,  and  during  the 
retreat  of  the  ice  the  dejjosition  of  a  deep  sheet  of  morainal  matter.  But 
there  is  no  unmodified  till  in  sight  near  the  south  end  of  the  lake,  and 
apparently  the  till  last  deposited  has  been  entirely  acted  on  by  the  glacial 
waters  so  as  now  to  be  a  part  of  the  plexus  of  retictilated  ridges  of  coarse 
gravel,  bowlderets,  and  bowlders  that  fill  the  A^alley.  This  .makes  the 
deposit  approach  in  character  the  overwash  or  frontal  plains  of  gravel  which 
extend  southward  from  the  terminal  moraines  of  the  continental  glacier. 
Ice  movements  probably .  converged  more  than  the  average  dejjth  of 
morainal  matter  here,  where  it  was  acted  on  by  the  subglacial  rivers. 

Within  a  half  mile  from  the  south  end  of  the  lake  the  gravel  of  the 
plains  just  described  becomes  finer,  and  within  2  miles  it  gradually  passes 
into  sand,  and  finally  into  clay  not  far  from  the  contour  of  230  feet.  A 
line  of  sedimentary  clays  extends  from  the  sea  nearly  to  the  lake,  and  30 
or  more  feet  above  the  contour  of  230  feet.  At  the  north  it  borders  the 
southern  part  of  the  gravel  and  sand  plain,  both  tei-minally  and  laterally. 
The  conditions  of  its  deposition  are  uncertain.  The  gravel  plain  apj)ears 
to  be  a  marine  delta  at  its  southern  extremity. 

From  the  foot  of  Sebago  Lake  a  discontinuous  series  of  broad,  table- 
like ridges  extends  southward  through  the  western  part  of  Grorham,  and 
thence  by  a  rather  meandering  course  to  near  Buxton  Post-Office,  where  it 
seems  to  end  in  a  delta  (probably  marine),  a  mile  or  more  in  length.  The 
intervals  between  the  successive  deposits  are  usually  less  than  one-fourth 
of  a  mile,  but  toward  the  north  they  are  somewhat  larger.  The  gravel 
plains  are  from  an  eighth  to  a  half  mile  in  diameter,  and  often  form  some- 
what rounded  caps  on  the  tops  of  hills,  especially  those  not  far  south  of 
Sebago  Lake.  This  series  lies  in  a  region  wholly  covered  by  the  marine 
clay,  unless  the  clay  near  Sebago  Lake  be  an  exception.  Perhaps  the 
whole  series  ought  to  be  named  the  Naples-Buxton  series.     The  gravels  in 


244  GLACIAL  GRAVELS  OF  MAINE. 

the  eastern  part  of  Grorham  and  in  Scarboro  may  have  been  deposited 
by  the  glacial  streams  that  formed  the  plain  at  the  foot  of  Sebago  Lake, 
but  more  probably,  if  those  gravels  have  any  connections,  they  will  be 
found  in  the  direction  of  Windham. 

SEBAGO  SERIES. 

A  well-defined  but  somewhat  discontinuous  series  of  glacial  gravels 
extends  for  several  miles  along  the  valley  of  Northwest  River  in  Sebago, 
and  joins  the  Naples-Standish  series  at  East  Sebago.  In  the  northwestern 
part  of  their  course  these  gravels  take  the  form  of  short  ridges,  but  for 
several  miles  above  East  Sebago  they  take  the  form  of  a  broad  osar  of 
fine  gravel  and  sand,  now  much  eroded.  This  series  is  probably  due  to  an 
overflow  from  the  direction  of  Great  Hancock  Pond,  as  will  be  described 
in  connection  with  the  following  series.  Further  description  of  the  plains 
extending  from  East  Sebago  into  Standish  and  Baldwin  will  also  be 
given  later. 

BRIDGTON-BALDWIN   SERIES. 

This  important  series  appears  to  begin  in  Sweden  as  a  small  ridge  of 
subangular  gravel  and  cobbles  situated  in  the  valley  of  a  small  stream 
v/hich  flows  southward  into  Highland  Lake.  The  ridge  is  on  the  side  of  a 
steep  hill  20  or  more  feet  above  the  stream,  and  there  is  no  corresponding 
ridge  or  terrace  on  the  opposite  side  of  the  valley.  It  must  therefore  be 
glacial  gravel.  Several  Islands  in  Highland  Lake  (Crotched  Pond)  show 
water-washed  gravel,  probably  glacial.  A  short  distance  from  the  south 
end  of  the  lake  one  of  these  islands  is  covered  with  gravel  which  is  quite 
certainly  glacial,  while  a  large  and  broad  osar  ridge  comes  out  of  the 
water  at  the  south  end  of  the  lake,  forming  in  part  the  barrier  which 
dammed  back  the  waters  of  the  lake.  It  thus  appears  probable  that  a 
single  glacial  river  flowed  from  Sweden  southward  across  the  basin  of 
this  lake. 

A  series  of  low  ridges  and  hummocks  extends  from  the  lake  south- 
ward through  Bridgton  Village,  and  then  for  about  10  miles  the  series  fol- 
lows the  very  low  valley  along  which  is  constructed  the  Bridgton  and 
Saco  River  Railroad.  Excavations  in  Bridgton  Village  show  pretty  well- 
rounded,  glacial  gravel  overlying  till,  and  a  gradual  transition  between 
them.     In  several  places  this  series  takes  the  form  of  an  osar-ridge  of  coarse 


BRIDGTON-BALDWIN  SERIES.  245 

matter,  bordered  on  each  side  by  a  level  plain  of  sand  up  to  about  one- 
fourth  mile  in  breadth.  It  is  an  instructive  instance  of  the  broad  osar.  At 
Sandy  Creek  Village  even  the  central  parts  of  the  plain  are  sandy.  The 
valley  followed  by  the  railroad  is  a  remarkably  level  pass  through  the  high 
hills  of  southern  Bridgton  and  the  eastern  part  of  Denmark.  Near  the 
east  line  of  Hiram  and  at  the  north  end  of  Barker  Pond  the  gravels  turn 
abruptly  south,  while  the  railroad  continues  its  southwest  course  to  Hiram 
station.  The  glacial  river  here  took  its  course  southward  along  the  sides 
of  Barker  and  Southeast  ponds,  and  then  it  flowed  up  and  over  a  hill  100 
or  more  feet  high.  On  the  north  slope  of  this  hill  are  several  horizontal 
terraces  of  sand  at  various  heights  above  Southeast  Pond  I  found  no 
recently  blown  sand  in  the  region,  and  these  terraces  have  the  shapes  of 
beaches  rather  than  the  rounded  outlines  of  sand  dunes.  A  considerable 
erosion  has  been  effected  by  small  brooks  which  here  and  there  liave  cut 
through  the  terraces  at  right  angles.  I  do  not  see  how  the  terraces  can  be 
due  to  unequal  erosion  by  streams  of  a  once  continuous  plain  of  sand.  The 
place  deserves  careful  study.  The  brief  examination  I  was  able  to  give  it 
suggested  that  the  terraces  were  beaches  formed  at  the  edge  of  a  body  of 
water  the  surface  of  which  was  gradually  falling.  I  saw  no  sign  of  an 
erosion  of  the  till.  More  probably  a  broad,  continuous  osar-plain  of  sand 
was  deposited  on  the  hillside,  and  this  could  easily  be  eroded  by  even  small 
waves,  so  as  to  form  cliffs  of  erosion  and  corresponding  beach  terraces 
transverse  to  the  slope  of  the  osar-plain.  At  several  excavations  in  the 
terraces  bowlders  from  2  to  6  feet  in  diameter  were  seen  in  the  midst  of  the 
sand.  They  were  till  bowlders,  not  the  rounded  ones  of  the  glacial  gravels. 
Wind  might  have  covered  the  bowlders  with  sand,  but  can  not  account  for 
their  having  been  dropped  upon  previoiisl}''  deposited  sand.  At  the  exposures 
examined  the  bowlders  were  surrounded  on  all  sides  by  well-assorted  sand, 
and  there  was  nothing  resembling  till  upon  or  within  the  sand — only  a  few 
isolated  bowlders,  whereas  the  till  contains  more  small  stones  than  large. 
If  they  were  dropped  from  the  roof  of  a  subglacial  tunnel,  the  tunnel  must 
have  been  fully  one-fourth  of  a  mile  wide,  and  we  inust  account  for  the 
presence  of  only  a  few  bowlders  instead  of  a  sheet  of  till.  The  theoretical 
questions  arising  in  connection  with  this  locality  will  be  discussed  more 
fully  later. 

Having  crossed  the  hill  south  of  Southeast  Pond,  the  glacial  river  next 


246  GLACIAL  GRAVELS  OF  MAINE. 

crossed  the  valley  of  Breakneck  Brook,  a  small  stream  whicli  flows  south- 
west to  West  Baldwin.  It  occupies  a  valley  bordered  by  high  hills  through 
which  there  is  but  one  pass  southward.  The  glacial  river  flowed  through 
this  pass  to  East  Baldwin  over  a  hill  210  feet  by  aneroid  above  the  point 
where  it  crossed  Breakneck  Brook,  and  probably  from  250  to  300  feet 
above  Southeast  Pond.  Up  and  over  such  high  hills  this  large  glacial  river 
flowed,  and  it  has  left  us  some  interesting  questions  to  solve.  The  gla- 
cial sediments  form  a  broad  osar  one-fourth  of  a  mile  wide,  though  some- 
what narrower  in  the  pass  toward  East  Baldwin.  Near  the  tops  of  the 
hills  the  sediment  is  scanty.  In  the  valley  of  Breakneck  Brook  and  toward 
the  base  of  the  south  slopes  the  material  is  very  coarse,  while  on  the  north 
slopes  it  is  sand  or  fine  gravel.  The  sheet  of  sand  and  fine  gravel  on  the 
north  slope  of  the  hill  crossed  by  the  system  just  south  of  Breakneck  Brook 
has  been  much  eroded  by  raius,  springs,  and  a  small  brook,  but  no  forms 
at  all  like  the  horizontal  terraces  that  overlook  Southeast  Pond  have  been 
produced.  On  this  slope  there  are  numerous  till-shaped  bowlders  2  to  6 
feet  in  diameter  lying  upon  and  within  the  sand  and  fine  gravel.  One  exca- 
vation at  the  roadside  shows  several  unpolished  bowlders  lying  upon  8  feet 
of  sand  and  fine  gravel,  and  the  excavation  does  not  reach  the  bottom  of 
the  sand.  Evidently  we  have  here  substantially  the  same  problem  as  that 
concerning  the  bowlders  2  or  3  miles  north,  in  the  sand  terraces  on  the  hill 
south  of  Southeast  Pond,  except  that  the  sediment  is  here  somewhat  coarser. 
Approaching  East  Baldwin  this  series  expands  into  plains  of  sand,  gravel, 
and  cobbles  which  are  confluent  with  the  other  great  plains  of  Baldwin, 
Standish,  Limington,  and  HoUis. 

TRIBUTARY   BRANCHES. 

Three  short  series  of  ridges  join  the  main  series  in  the  eastern  part 
of  Denmark.  They  were  deposited  by  small  streams  that  carried  ofi'  the 
glacial  waters  of  the  broad  basin  in  Denmark  and  Sweden  in  which  Moose 
Pond  is  situated. 

DELTA  BRANCHES. 

A  delta  branch  probably  left  this  series  near  the  south  end  of  Great 
Hancock  Pond.  At  this  point  a  broad  deposit  of  sand  and  gravel  diverged 
from  the  main  osar-plain  and  extends  for  about  one-fourth  of  a  mile  up  a 
hill  toward  the  south  and  east.     Directly  in  front  is  a  low  pass  lying  east 


BEIDGTON-BALDWIN  SEEIES.  247 

of  Beecli  Hill,  Sebago.  The  gravel  soon  becomes  discontinuous,  and  at 
the  top  of  the  col  I  could  not  discover  any  gravel.  The  gravels  before 
described  as  the  Sebago  series  begin  a  short  distance  south  of  this  point. 
These  facts  make  it  probable  that  a  glacial  stream  overflowed  from  Great 
Hancock  Pond  over  the  divide  and  down  the  valley  of  Northwest  River  to 
East  Sebago. 

Another  delta  branch  diverged  from  the  main  series  at  the  point  where 
it  crosses  Breakneck  Brook  and  followed  the  valley  of  that  stream  soath- 
westward.  Originally  a  plain  of  coarse  gravel,  cobbles,  and  bowlderets 
extended  across  the  narrow  valley  to  a  height  of  20  to  40  feet  above  the 
present  level  of  the  brook.  This  plain  has  been  much  eroded  along  the 
central  part  of  the  valley,  so  that  now  small  lateral  terraces  along  the  sides 
of  the  valley  are  all  that  remain  of  the  original  plain.  By  aneroid  this 
brook  falls  200  feet  in  flowing  from  where  it  leaves  the  main  osar-plain  to 
West  Baldwin,  a  distance  of  about  3  miles.  With  such  a  rapid  fall  it  is 
not  surprising  that  only  coarse  sediment  was  dropped  in  the  valley.  At 
West  Baldwin  this  series  becomes  confluent  with  the  great  plains  of  the 
Saco  Valley. 

The  history  of  the  osar-plain  in  Breakneck  Valley  appears  to  be  about 
as  follows:  At  first  the  Bridgton  glacial  river  flowed  across  the  valley,  then 
up  and  over  the  hill  210  feet  high  to  East  Baldwin.  This  becomes  evident 
when  we  consider  that  if  the  channel  had  first  been  opened  southwest  on  a 
down  slope  of  60  feet  per  mile  it  is  extremely  improbable  that  the  water 
could  subsequently  have  been  diverted  over  a  hill  210  feet  high.  The 
stream  to  East  Baldwin  has  deposited  much  more  sediment  at  its  terminal 
plains  than  the  other  stream  to  West  Baldwin,  and  if  the  former  stream  was 
not  the  earlier,  no  reason  can  be  assigned  why  the  larger  flow  should  take 
place  along  its  course.  After  the  channel  was  opened  southwest  down  the 
Breakneck  Valley  the  water  would  all  flow  that  way,  unless  in  time  of 
extraordinary  flood. 

Few  if  any  students  of  the  drift  can  see  the  great  contrast  in  compo- 
sition between  the  broad  osar  of  the  Bridgton-Baldwin  series  and  the 
adjacent  till,  or  see  it  rejecting  valleys  of  natural  drainage  in  order  to  go 
up  and  over  hills  more  than  200  feet  higher  than  the  ground  to  the  north, 
without  admitting  the  utter  impossibility  of  accounting  for  such  plains  of 
sand   and    gravel    in   such    situations    by  any   freak  of   eolian,  fluviatile, 


248  GLACIAL  GRAVELS  OF  MAINE. 

lacustriue,  or  marine  action.     No   way  remains  for  accounting  for  these 
plains  except  dy  the  action  of  glacial  streams  confined  between  ice  walls. 

ALBANY-SACO    RIVER    SERIES. 

Measured  by  the  amount  of  assorted  matter  which  it  contains,  this 
is  one  of  the  greatest  gravel  series  or  systems  in  the  State. 

The  northern  connections  are  obscure,  and  involve  one  of  the  most 
difficult  questions  relating  to  the  drift  of  Maine,  i.  e.,  the  determination 
of  the  true  history  of  the  sedimentary  drift  of  the  Androscoggin  Valley 
from  Bethel  westward  to  the  White  Mountains.  The  pebbles,  cobbles,  and 
bowlderets  of  the  central  parts  of  this  sedimentary  drift  of  the  Andros- 
coggin are  as  well  rounded  as  those  in  the  kame  plains,  and  usually  more 
so  than  those  in  the  beds  of  the  White  Mountain  streams  having  a  fall 
of  100  feet  or  more  per  mile.  In  places  the  alluvium  of  the  main  valley 
rises  considerably  above  that  of  the  lateral  valleys.  In  a  word,  most  of 
this  drift  presents  all  the  external  characters  of  the  broad  osar  or  plain. 
Also  in  some  places  reticulated  ridges  are  common,  and  there  are  many 
kettleholes  and  some  lakelets  in  the  plain,  thereby  presenting  the  features 
of  the  plains  of  reticulated  kames.  At  Bethel  the  character  of  the  alluvium 
of  the  valley  rapidly  changes.  Instead  of  the  terraced  plains  of  coarse 
matter,  which  are  found  from  Gorham,  New  Hampshire,  to  Bethel,  the 
drift  of  the  valley  from  the  last-named  place  eastward  becomes  finer,  and 
consists  almost  wholly  of  clay  and  sand,  except  where  the  osar-plains 
crossed  the  valley,  as  at  Rumford  Point  and  in  part  of  the  valley  from 
the  Swift  River  to  Canton.  My  explorations  of  this  portion  of  the  Andros- 
coggin Valley  were  made  before  I  had  fully  distinguished  the  osar-plain, 
and  I  was  then  chiefly  occupied  in  studying  the  work  done  by  the  local 
glacier  which,  for  a  time  after  the  general  ice  movement  ceased,  filled  the 
valley  as  far  east  as  West  Bethel.  I  do  not  therefore  assert  positively 
that  the  plain  of  coarse  alluvium  that  extends- from  the  White  Mountains 
east  to  a  point  about  a  half  mile  west  of  Bethel  Village  is  chiefly  glacial 
gravel,  but  all  my  later  studies  point  to  that  conclusion.  The  relation  of 
the  earher  osar  or  osar-plain,  if  it  existed,  to  the  local  glacier,  will  form 
an  interesting  subject  for  study,  as  will  also  the  distinguishing  of  an  osar- 
plain  proper  from  frontal  gravels  deposited  while  the  ice  -was  retreating 
up  the  valley.     The  probable  course  of  this  glacial  stream  was  down  the 


ALBANY-SACO  RIVER  SERIES.  249 

valley  of  the  Androscoggin  to  near  Bethel  Village,  where  it  turned  south 
along  the  low  valley  in  which  was  once  surveyed  a  route  for  a  canal  from 
Bethel  down  the  valley  of  Crooked  River  to  Sebago  Lake  and  thence  to 
Portland.  This  valley  lies  a  short  distance  west  of  Bethel  Village,  on  the 
west  side  of  the  hill  lying  south  of  Bethel  called  Paradise  Hill.  There  is 
considerable  reason  to  suspect  that  there  is  an  osar-plain  of  fine  matter  in 
the  bottom  of  this  valley,  disguised  by  some  valley  drift.  At  one  time 
there  was  an  overflow  of  the  Androscoggin  south  through  this  low  pass, 
also  down  another  valley  which  leads  south  from  the  broad  Bethel  intervale 
past  the  east  base  of  Paradise  Hill  and  joins  the  other  valley  just  south 
of  this  hill.  The  intervale  was  then  a  lake  3  or  more  miles  wide.  The 
alluvial  plains  that  fill  these  two  valleys  which  lead  south  from  near  Bethel 
may  possibly  be  Avholly  fluviatile  drift,  formed  during  this  overflow  of  the 
Androscoggin  southward,  yet  I  provisionally  mark  a  glacial  stream  as 
flowing  down  the  Androscoggin  to  Bethel  and  thence  southward.  There 
may  have  been  glacial  overflows  from  the  Sunday  River  and  Bear  River 
valleys.  In  Albany,  near  the  top  of  the  low  pass  that  leads  south  from 
Bethel,  gravel  unmistakably  glacial  is  found,  and  continues  in  the  form  of 
bars,  ridges,  and  terraces  down  the  valley  of  Crooked  River  to  North  Water- 
ford.  The  gravels  have  been  considerably  eroded  by  the  sti-eam,  and  it  is 
uncertain  whether  the  original  form  of  these  deposits  in  northern  Albany 
was  that  of  a  broad  osar-plain  extending  across  the  valley  or  whether  there 
were  two  or  more  distinct  ridges.  In  the  southern  part  of  Albany  and  the 
northern  part  of  Waterford  there  is  a  well-defined  two-sided  ridge  of  gravel 
and  cobbles  in  the  midst  of  the  valley,  and  in  a  few  places  there  are  two 
such  ridges,  bordered  by  plains  or  terraces  of  rather  fine  sand  and  gravel 
having  nearly  horizontal  stratification.  These  extend  across  the  valley, 
which  is  near  a  half  mile  in  width,  at  two  places,  but  in  most  of  its  course 
is  but  little  more  than  half  that  breadth. 

The  alluvial  drift  of  the  Crooked  Rivei-  Valley  is  of  composite  origin. 

1.  We  have  a  broad  deposit  of  glacial  gravel  taking  the  form  of  a 
broad  osar,  with  some  distant  osar  ridges  in  the  midst  of  it. 

2.  There  must  have  been  considerable  stream  wash  from  the  rather 
steep  hills  which  border  the  valley,  especially  as  there  are  few  lakes  and 
ponds  in  the  region  and  the  floods  are  rather  violent.  The  drainage  basin 
is  rather  small,  however. 


250  GLACIAL  GEAVELS  OF  MAINE. 

3.  There  were  two  overflows,  each  raore  than  one-eighth  of  a  mile 
wide,  from  the  Androscoggin  Valley  in  Bethel  soutliAvard  through  Albany 
and  down  the  Crooked  River  Valley.  These  took  place  after  the  ice  had 
melted  over  the  broad  Bethel  intervale,  and  apparently  over  the  Crooked 
River  Valley  also.  Their  waters  probably  deposited  most  of  their  sedi- 
ments before  flowing  over  the  col  in  Albany.  As  these  Androscoggin 
waters  rushed  down  the  valley  they  woidd  more  or  less  wash  away  and 
reclassify  the  glacial  gravel  previously  deposited. 

It  thus  becomes  specially  difficult  to  determine  whether  the  plain  of 
finer  sediments  that  borders  the  ridges  which  rise  a  few  feet  above  the  rest 
of  the  plain  is  osar-plain  or  valley  drift  or  both.  The  ridges  were  without 
doubt  deposited  in  narrow  channels  within  ice  walls.  From  general  analogy 
it  is  probable  that  the  original  channel  broadened  and  that  an  osar-plain 
was  laid  down  in  the  broad  channel,  and  that  this  was  subsequently  acted 
UDon  by  river  floods  and  covered  by  some  valley  drift. 

At  North  Waterford  the  Crooked  Rivei-  turns  abruptly  eastward,  and 
for  several  miles  it  is  bordered  by  erosion  terraces  of  gravel  and  well- 
rounded  cobbles.  Apparently  a  continuous  plain  one-eighth  to  more  than 
one-fourth  mile  wide  once  extended  across  the  whole  valley.  In  the  eastern 
part  of  Waterford  the  river  again  turns  a  right  angle  and  flows  southward. 
The  valley  here  widens  for  2  or  3  miles,  but  the  gravel  plain  does  not 
broaden  correspondingly.  It  takes  the  form  of  a  plain  three-fourths  of  a 
mile  wide  and  about  twice  as  long,  situated  on  the  west  side  of  the  river. 
At  the  north  it  consists  chiefly  of  coarse  gravel,  cobbles,  and  bowlderets, 
all  very  much  rounded.  Although  rather  level  on  the  top,  the  plain  incloses 
Papoose  Pond  and  several  kettleholes.  Toward  the  south  it  becomes  some- 
what finer  in  composition,  yet  it  ends  in  gravel  which  contains  some  cob- 
bles and  large  pebbles.  It  can  not,  therefore,  be  a  delta  deposited  in  a 
large  body  of  still  water.  Along  the  eastern  side  of  this  gravel  plain  and 
for  several  miles  below  this  point  the  valley  of  Crooked  River  is  covered 
by  a  plain  of  sand  one-eighth  to  one-third  of  a  mile  wide.  This  is  often 
very  fine  and  silty,  and  sometimes  contains  a  little  angular  gravel  near  the 
stream,  the  result  of  the  erosion  of  the  till.  The  contrast  in  shape  between 
this  gravel  and  that  contained  in  the  present  bed  of  the  stream  as  compared 
with  the  very  round  stones  of  the  gravel  plain  that  extends  from  North 


ALBANY-SACO  RIVER  SERIES.  251 

Waterford  to  Papoose  Pond  is  veiy  great,  and  shows  that  the  gravels  of 
the  osar-plain  have  been  subjected  to  much  more  attrition.  Going  south- 
ward in  the  valley,  the  lower  layer  of  the  valley  drift  becomes  clayey.  It 
is  overlain  by  sand  containing  some  angular  gravel — mere  tillstones  which 
are  scarcely  polished.  The  plain  of  valley  drift  rises  20  to  30  feet  above 
the  present  bed  of  the  river,  which  is  bordered  by  two  and  sometimes  three 
terraces  of  erosion.  At  Edes  Falls,  in  Otisfield,  the  undei'clay  is  overlain 
by  several  feet  of  subangular  gravel,  sufficiently  worn  to  suggest  glacial 
origin.  Perhaps  there  are  local  kames  somewhere  in  the  midst  of  the  val- 
ley and  part  of  the  gravel  was  washed  away  by  river  floods  and  spread 
over  the  previously  deposited  underclay.  No  kames  appeared  near  this 
place  in  the  banks  of  the  river,  but  they  may  be  situated  near  by  and  are 
now  hid  by  the  valley  drift.  South  of  Edes  Falls  the  plain  of  valley  drift 
is  in  general  from  a  half  mile  to  more  than  a  mile  in  breadth.  The  lower 
stratum  is  clay,  while  the  upper  is  a  thick  layer  of  sand,  which  in  many 
places  has  blown  into  low  dunes.  For  several  miles  north  of  Sebago  Lake 
the  upper  and  lower  layers  of  the  valley  alluvium  have  about  the  same 
composition,  and  both  are  a  fine  silty  sand.  As  stated  elsewhere,  the  river 
here  has  eroded  a  channel  bordered  by  steep  cliffs  of  silt,  and  there  are  no 
higher  erosion  terraces,  i.  e.,  the  rates  of  erosion  and  deposition  are  here 
substantially  equal.  The  upper  end  of  the  original  basin  of  Sebago  Lake 
has  been  silted  up  for  2  or  3  miles,  and  perhaps  farther.  The  Crooked 
River  unites  with  the  outlet  of  Long  Pond  to  form  the  Songo,  which  mean- 
ders back  and  forth  in  a  remarkable  manner.  This  stream  has  been 
celebrated  by  Longfellow  in  his  song  of  "The  Songo  River." 

We  thus  see  that  true  osar-ridges  extend  from  Albany  down  the 
Crooked  River  Valley  to  North  Waterford.  Then  for  several  miles  the 
valley  contains  a  plain  of  gravel,  with  cobbles  and  bowlderets  too  large 
and  too  round  to  be  a  part  of  the  valley  drift,  and  ending  in  a  broader 
plain  showing  some  of  the  characteristics  of  a  delta,  but  not  such  a  delta 
as  should  form  at  the  end  of  such  a  large  glacial  river  as  flowed  through 
Albany  to  North  Waterford.  Then  for  many  miles,  to  Sebago  Lake,  there 
is  nothing  in  the  valley  that  resembles  the  drift  of  the  upper  valley  or  that 
can  be  considered  as  glacial  gravel  proper,  unless  it  be  a  short  deposit  near 
Edes  Falls.     That  a  large  glacial  river  should  end  in  that  small  plain  at 


252  GLACIAL  GRAVELS  OF  MAINE. 

Papoose  Pond  near  East  Waterford  seemed  so  unusual  that  it  demanded 
further  investigation,  although  as  yet  I  did  not  have  even  a  hint  of  the 
true  condition  of  things  at  North  Waterford. 

As  stated  already,  the  Crooked  River  turns  abruptly  east  at  North 
Waterford.  From  where  the  river  turns  east  another  valley  leads  south- 
west, so  low  that  a  dam  of  50  or  75  feet  would  probably  turn  the  Crooked 
River  southwest  into  the  Saco  River.  Kezar  Brook  originates  in  the  Five 
Kezar  Ponds,  only  about  2  miles  from  North  Waterford,  and  flows  south- 
westward  in  this  valley. 

DELTA  BRANCH  AT  NORTH  WATERFORD. 

I  have  long  since  learned  that  glacial  rivers  bear  careful  watching. 
Their  deceitfulness  is  well  exhibited  at  North  Waterford.  At  the  time  of 
my  first  visit  to  this  region,  in  1878,  diverging  or  delta  branchings  of  osar 
systems  were  unknown  to  me.  I  then  went  for  about  a  mile  down  the  river 
below  North  Waterford  and  found  the  gravel  extending  down  the  river.  I 
inferred  there  was  a  Crooked  River  series,  of  which  the  gravel  at  Ede's 
Falls,  which  had  been  described  to  me,  was  a  part.  Several  years  later  I 
explored  the  whole  valley  and  discovered  that  the  glacial  gravel  ends  near 
East  Waterford  in  the  plain  at  Papoose  Pond.  A  full  investigation  then 
followed.  Two  branches  of  the  glacial  river  that  came  down  from  Albany 
diverged  at  North  Waterford.  The  smaller  one  followed  the  Crooked  River 
Valley  a  few  miles  to  Papoose  Pond.  The  larger  one  crossed  a  low  col  and 
followed  the  valley  of  Kezar  Brook  southwestward.  For  several  miles 
gravel  takes  the  form  of  a  series  of  ridges  and  terraces  of  coarse  osar 
material.  Some  of  these  ridges  are  more  than  50  feet  high  and  are  very 
broad  and  massive.  Approaching  Lovell  Village,  the  series  takes  the  form 
of  sand  plains,  having  a  gently  rolling  surface,  as  if  the  sand  had  been 
deposited  in  a  broad  channel  upon  graA^el  ridges  which  had  previously  been 
formed  in  narrower  channels.  The  sand  plain  is  here  near  a  mile  wide. 
The  series  here  leaves  the  valley  of  Kezar  Brook  and  turns  abruptly  south- 
ward over  a  rolling'  plain.  It  passes  through  Sweden,  Fryeburg,  and  Den- 
mark, and  enters  the  Saco  Valley  about  2  miles  east  of  East  Brownfield. 
In  all  this  part  of  its  course  it  is  a  kind  of  osar-plain,  not  so  level  on  tlie 
top  as  most  osar-plains,  and  containing,  at  least  on  the  top,  much  sand  or 


NORTH  WATERFORD  BRANCH.  253 

very  fine  gravel.  It  skirts  the  Avestern  base  of  Pleasan.  Mountain  and  the 
eastern  side  of  Kezar  Pond  and  two  other  small  ponds  in  Fryelouro-.  The 
origin  of  these  ponds  is  discussed  elsewhere. 

For  25  miles  this  great  series  is  seldom  less  than  one-fourth  of  a  mile 
wide,  and  it  often  has  three  or  four  times  that  breadth.  No  central  domi- 
nant ridge  could  be  distinguished  at  the  places  examined.  If  such  there 
was,  it  has  been  covered  by  the  sediments  which  were  brought  down  by  the 
rush  of  the  vast  river  which  in  later  times  swept  down  this  broad  thorough- 
fare of  waters.  The  great  volume  of  the  sediments  is  strongly  in  favor  of 
the  hypothesis  that  there  was  an  overflow  from  the  Androscoggin  Valley 
southward  through  Bethel  and  Albany  before  the  melting  of  the  ice. 

It  thus  appears  that  at  North  Waterford  there  were  two  valleys  widely 
diverging  and  that  glacial  gravels  were  deposited  in  each  valley.  The  val- 
ley of  Crooked  River  is  not  only  a  slope  of  natural  drainage,  but  it  is  also 
more  nearly  parallel  with  the  general  direction  of  the  ice  movement  in  that 
region.  Yet  by  far  the  larger  overflow  was  southwest,  along  a  route  more 
transverse  to  the  glaciation  and  over  a  low  divide,  rather  than  down  the 
drainage  slope.  The  breadth  of  the  gravel  plain  along  the  Crooked  River 
is  as  great  as  that  of  the  Kezar  Brook  series.  Both  series  were  deposited 
in  channels  that  were  probably  broad  enough  to  carry  oif  all  the  waters 
that  came  from  the  north  without  the  aid  of  the  other  channel. 

The  history  of  the  glacial  gravels  of  this  region  is  probably  as  follows : 
Originally  a  large  glacial  river  flowed  from  Albany  (and  perhaps  from 
Bethel  and  the  Androscoggin  Valley)  south  to  North  Waterford  and  along 
the  valley  of  Kezar  Brook  southwestward  to  Lovell  and  thence  south  to  the 
Saco  River.  At  first  this  river  flowed  in  a  narrow  channel  within  the  ice. 
Subsequently  other  ridges  were  deposited  in  channels  near  the  original  one. 
By  degrees  these  channels  became  confluent  and  the  channel  broadened, 
and  an  osar-plain  was  laid  down  in  the  broad  channel.  During  this  time 
the  valley  of  Crooked  River  was  blocked  by  ice,  so  that  the  glacial  river 
easily  flowed  southwest  over  the  divide.  But  the  time  came,  toward  the 
last  of  the  Ice  period,  when  the  waters  effected  a  passage  from  North  Water- 
ford eastward  down  the  valley  of  Crooked  River.  At  this  time  the  melting 
had  proceeded  so  far  that  the  valley  was  bare  of  ice  from  Sebago  Lake 
north  to  East  Waterford.     Hence  glacial  gravel  was  formed  from  North 


254  GLACIAL  GRAVELS  OF  MAINE. 

Waterford  only  as  far  south  as  the  plain  near  Papoose  Pond,  and  below 
there  the  water  flowed  as  an  ordinary  surface  stream,  and  only  fluviatile 
di'ift  was  deposited  in  that  part  of  the  valley;  at  least,  if  this  glacial  stream 
flowed  in  an  ice  channel  south  of  East  Waterford  it  was  so  narrow  as  not 
to  deposit  gravels,  or  else  the  glacial  gravels  are  now  covered  by  the 
valley  di'ift. 

Where  the  Albany  series  reached  the  Saco  River,  near  East  Brownfield, 
it  can  no  longer  be  distinguished  from  the  other  series  which  cover  a  large 
part  of  southwestern  Maine  with  a  closely  connected  network  of  gravel 
plains.  Above  this  point  the  drift  of  the  Saco  Valley  is  much  finer  in  com- 
position than  the  broad  plain  of  gravel,  cobbles,  and  bowlderets  which 
extends  from  this  point  south  and  east  along  the  valley  for  many  miles.  In 
the  middle  of  the  valley  the  stones  of  this  plain  are  very  much  worn  an^ 
rounded,  but  near  the  sides  of  the  plain  the  material  resembles  till,  which 
plainly  has  had  the  finest  detritus  washed  out  of  it,  but  with  hardly  any 
attrition.  I  repeatedl}'  saw  stones  and  bowlders  near  the  outer  margin  of 
the  upper  terrace  that  retained  their  till  shapes  with  only  very  small  modi- 
fication. This  appearance  was  especially  noticeable  at  an  excavation  near 
Brownfield  station  of  the  Maine  Central  Railroad. 

In  Hiram,  Baldwin,  and  northern  Limington  the  gravel  plain  of  the 
Saco  is  often  uneven  and  ridged  like  the  plains  of  reticulated  kames.  As 
we  go  southward  the  ]jlain  becomes  more  level  and  the  material  finer.  The 
coarse  gravel  gives  place  to  fine  gravel  and  this  passes  by  degrees  into 
broad  sand  plains  in  Standish,  southern  Limington,  and  Holhs,  where  the 
sand  ends  in  the  marine  clays.  The  plains  showing  reticulated  ridges  thus 
pass  by  degrees  into  the  marine  delta-plains.  These  deltas  were  deposited 
not  far  above  230  feet  in  the  open  sea,  and  are  the  largest  in  Maine. 

While  it  is  not  easy,  or  at  present  possible,  to  separate  the  Albany-East 
Brownfield  series  from  the  other  reticulating  plains  of  sand  and  gravel  near 
the  Saco  River  in  Brownfield,  Hiram,  Cornish,  Limington,  and  Baldwin, 
yet  the  great  size  of  the  series  toward  the  north  makes  it  certain  that  this 
great  glacial  river  contributed  a  large  proportion  of  these  plains.  Most  of 
the  gravel  series  of  southwestern  Maine  are  remarkable  for  the  height  of  the 
hills  which  they  cross,  but  this  series  penetrates  the  high  hills  that  lie  east 
of  the  White  Mountains  along  a  route  so  level  that  one  may  travel  from 
Gorham,  New  Hampshire,  eastward  to  Bethel,  and  thence  along  the  course 


ALLUVIAL  TEKEACES  OF  SACO  RIVEE.  255 

of  this  series,  without  having  to  rise  over  hills  higher  than  100  feet,  measured 
on  their  northern  slopes. 

ALLUVIAL    TERRACES    OF    THE    SACO    RIVER. 

From  the  sea  to  near  Bonnv  Eagle,  in  Standish,  the  Saco  River  is  bor- 
dered by  terraces  of  erosion  in  the  marine  beds.  Near  the  river  these 
marine  sediments  differ  but  little  from  those  found  at  a  distance  from  the 
river.  If  the  ice  had  melted  before  the  marine  beds  were  laid  down  and 
the  sea  advanced,  the  river  would  have  begun  to  flow  before  the  deposition 
of  the  clays,  and  we  should  now  find  a  plain  of  valley  drift  overlain  by  the 
marine  beds.  The  fact  that  these  beds  are  substantially  the  same  near  and 
far  away  from  the  river  valleys  shows  that  the  rivers  had  not.  begun  to  flow 
at  the  time  of  their  deposition,  and  that  they  were  a  rather  deejj-water 
formation. 

Near  Bonn}'  Eagle  the  Saco  enters  the  great  marine  deltas  brought 
down  by  the  glacial  rivers,  overlain  by  the  delta  of  the  river  after  the  melt- 
ing of  the  ice  That  the  glacial  deltas  were  deposited  in  the  open  sea  is 
proved  by  the  fact  that  they  are  confluent  and  practically  continuous  over 
a  broad  area  extending  from  Standish  southwestward  through  Limington, 
Hollis,  Lyman,  Waterboro,  Alfred,  and  Sanford,  to  North  Berwick.  For  a 
few  miles  above  Bonny  Eagle  the  erosion  terraces  of  the  Saco  are  exca- 
vated in  sand  overlying  clay.  Then  the  gravel  appears,  and  above  Steep 
Falls  coarse  gravel,  cobbles,  bowlderets,  and  some  bowlders  form  a  large 
part  of  the  river  terraces.  Where  there  are  broad  plains  of  porous  gravel 
bordering  the  river  there  is  usually  more  erosion  than  in  the  narrow  parts 
of  the  valley  This  is  due  largely  to  the  action  of  subterranean  waters  in 
the  manner  elsewhere  described. 

North  of  Hiram  lie  a  number  of  broad,  rather  level  valleys  opening 
southward.  This  would  tend  to  converge  the  ice  into  the  narrower  valley 
of  the  Saco  extending  from  this  point  south  and  east.  Late  in  the  Ice 
period  as  the  ice  retreated  there  would  naturally  be  a  local  glacier  in  the 
valley,  i  e.,  one  following  the  valley  independently  of  the  previous  general 
movement.  It  is  a  difficult  problem  now  to  determine  how  much  of  the 
deep  sheet  of  water-assorted  matter  that  covers  the  Saco  Valley  from 
Hiram  to  Steep  Falls  was  deposited  during  the  general  movement  and  how 
much  was  the  work  of  the  more  local  glacier.     As  the  ice  retreated  up  the 


256  GLACIAL  GEAYELS  OF  MAINE. 

valley  the  terminal  moraine  of  this  supposed  glacier  would  naturally  fall 
into  the  subglacial  rivers  and  be  modified  by  water,  thus  helping  to  form 
an  overwash  or  frontal  plain  in  front  of  the  ice  as  it  receded. 

Above  Hiram  the  part  of  the  valley  covered  by  alluvium  broadens 
into  a  plain,  in  Brownfield  and  Fryeburg,  near  10  miles  in  diameter.  The 
floods  of  valley  drift  in  time  covered  the  whole  of  this  broad  area,  so  that 
it  would  present  the  appearance  of  a  lake.  In  this  was  deposited  a  broad 
fluvial  delta  extending  from  Conway,  New  Hampshire,  east  to  Lovell  and 
Brownfield.  For  many  miles  in  this  broad  sedimentary  plain  the  river 
winds  very  circuitously  and  is  bordered  by  only  a  single  bluff  of  erosion — 
that  which  forms  its  banks.  This  indicates  that  erosion  and  deposition  are 
here  going  on  at  about  the  same  rate.  The  alluvial  plain  narrows  as  we 
approach  the  New  Hampshire  line,  and  the  drift  becomes  coarser  and  con- 
tains much  rounded  gravel.  The  erosion  terraces  along  the  Saco  River 
vary  from  10  to  about  50  feet  in  height  above  the  river. 

THE  GREAT  COMPLEX  OF  NORTHWESTERN  YORK  AND  SOUTHWESTERN 
OXFORD  COUNTIES. 

This  is  a  series  of  plains  closely  connected  by  lateral  series  so  as  to 
cover  as  with  a  network  the  hilly  country  lying  west  and  southwest  of  the 
Saco  as  far  as  the  valley  of  the  Mousam  River.  In  this  complex  series  it 
is  difficult  to  distinguish  tributary  from  delta  branches.  On  the  west  these 
gravels  are  connected  by  three  lines  of  gravel  plains  with  the  great  kame 
system  described  by  Mr.  Warren  Upham  in  the  reports  of  the  New  Hamp- 
shire geological  survey  as  extending  from  Conway,  New  Hampshire,  south- 
ward to  the  valley  of  the  Ossipee  Lakes.  Two  of  these  plains  (in  the 
form  of  osar-plains  about  one-fourth  of  a  mile  wide)  extend  from  Effing- 
ham, New  Hampshire,  into  Parsonsfield,  Maine,  while  a  tract  of  reticulated 
ridges  nearly  3  miles  wide  passes  from  Wakefield,  New  Hampshire,  into 
Newfield  and  Acton,  Maine. 

The  region  between  the  Saco  and  the  Mousam  is  diversified  by  numer- 
ous ranges  of  hills.  If  we  start  south  from  the  broad  hill-encircled  plain 
of  Fryeburg,  which  on  a  small  scale  much  resembles  in  form  the  "parks"  of 
the  Rocky  Mountains,  we  almost  immediately  enter  the  hilly  country.  In 
Porter,  Brownfield,  Parsonsfield,  and  Cornish  many  of  the  higher  hills  rise 
to  800  feet  or  higher,  and  the  slopes  are  rather  steep.  Going  southward, 
we  find  the  valleys  becoming  broader  and  the  hills  lower  and  with  gentler 


COMPLEX  IX  YOKK  AXD  OXFOED  COUXTIES.        257 

slopes.  Not  far  from  the  line  of  the  Portland  and  Rochester  Railroad  we 
pass  into  a  gently  rolling  plain,  out  of  which  rise  a  few  granite  knobs  and 
other  hills,  like  Bauneg  Beg  and  Agamenticus.  This  plain  extends  to  the 
sea.  In  the  tract  of  country  here  described  there  is  no  single  dominant 
range  of  hills.  There  are  two  systems  of  valleys,  nearly  at  right  angles 
to  each  other.  The  larger  streams,  such  as  the  Great  and  Little  Ossipee 
rivers,  flow  eastward  into  the  Saco.  The  north-and-south  valleys  are 
occupied  by  numerous  lateral  tributaries  of  the  principal  streams.  This 
arrangement  of  valleys  will  in  part  account  for  the  somewhat  rectangular 
shape  of  some  of  the  reticulations  of  this  complex  series.  The  local  rock 
of  this  region  is  chiefly  granitic,  and  this  rock  in  Maine  always  affords  an 
abundance  of  till.  In  the  more  hilly  country  the  glacial  gravel  is  in  gen- 
eral quite  coarse,  containing  multitudes  of  much-rounded  bowlderets  and 
bowlders  up  to  4  feet  in  diameter.  Broad  sheets  of  rounded  gravel,  etc., 
frequently  have  numerous  large  till-shaped  bowlders  resting  upon  them, 
but  these  ai-e  mostly  below  230  feet,  and  may  have  been  deposited  by  ice 
floes.  Numbers  of  short  tributary  branches  come  down  the  slopes  of  hills 
to  join  the  main  plains,  and  even  these  short  hillside  branches  show  large 
rounded  bowlders.  Along  the  principal  lines  of  glacial  overflow  the  stones 
are  much  worn  and  rounded,  yet  here  and  there  they  are  subangular  and 
differ  in  shape  but  little  from  those  of  the  till.  Such  areas  are  usually  on 
the  borders  of  the  plains. 

The  number  and  height  of  the  hills  which  the  gravels  of  this  region 
cross  are  remarkable.  Nowhere  else  in  Maine  is  there  anything  equal  to 
them.  In  Brownfield,  Porter,  and  Hiram  the  glacial  rivers  flowed  u-p  and 
over  these  hills  200  or  more  feet  higher  than  the  valleys  to  the  north  of 
them,  and  in  Parsonsfield  and  Cornish  they  crossed  several  more.  In  Lim- 
ington,  near  the  Cornish  line,  a  gravel  series  goes  up  and  over  a  pass  in  a 
narrow  valley  called  "The  Notch,"  at  the  western  base  of  Strouts  Moun- 
tain. The  top  of  the  pass  is  fully  300  feet  above  the  northern  base  of  the 
hill  and  about  400  feet  above  the  same  gravel  series  at  the  Saco  River,  2 
or  3  miles  north  of  The  Notch.  These  measurements  were  made  with  the 
aneroid  barometer,  but  I  have  tried  to  make  the  figures  here  given  under 
the  truth  rather  than  over  it.  Near  the  tops  of  the  higher  hills  the  gravel 
is  scanty,  and  then  for  a  half  mile  or  more  sometimes  none  will  be  found 
on  the  southern  slopes.     These  branching  series  often  rej  act  valleys  of 

MON  XXXIV 17 


258 


GLACIAL  GEAVELS  OF  MAINE. 


favorable  slopes  iu  order  to  climb  hills,  and  are  therefore  difficult  to  map. 
Delta  branches  are  liable  at  any  point  to  diverge  from  the  series  one  is 
exploring,  and  constant  watchfulness  is  required. 

The  map  shows  the  courses  of  these  connected  series  more  clearly 
than  any  verbal  description,  yet  in  the  absence  of  maps  showing  the  relief 
forms  of  the  land  it  may  be  best  briefly  to  describe  the  glacial  gravels  of 
three  townships  as  a  specimen  of  the  whole  region  now  under  consideration. 

Near  the  southern  end  of  the  Fryeburg  Valley  the  glacial  gravels 
begin,  and  extend  southward  along  a  low  pass  between  the  conical  peaks 


f^^^M 


Fig.  24.— Broad  osar  penetrating 


pass  over  hill  400  feet  high ;  Liraington. 


known  as  Tibbitts  and  Peavys  hills.  The  line  of  gravels  llien  descends 
about  100  feet  into  the  east-and-west  valley  of  Pequawket  Stream.  It 
here  divides  into  three  delta  branches.  One  series  crosses  the  valley 
nearly  at  right  angles  and  ascends  the  long  hill  which  lies  to  the  south 
along  the  south  branch  of  Pequawket  Stream  to  a  height  of  fully  200  feet. 
Another  branch  turns  east  and  follows  the  Pequawket  Valley  through 
Brownfield  Village,  when  it  soon  expands  into  a  broad  plain  reaching  to 
East  Brownfield,  southeast  of  which  place  it  becomes  confluent  with  the 
gravels  of  the  Albany-Saco  River  series.     This  plain  shows  the  horizontal 


X       ^ 

o     ^ 


COMPLEX  IN  YORK  AND  OXFORD  (JOUNTIES.  259 

assortment  of  sediments  characteristic  of  the  deka-plain,  and  this  broad 
and  level  valley  near  East  Browufield  was  at  one  time  occupied  by  a  lake, 
or  a  river  so  broad  as  to  resemble  a  lake.  The  third  diverging  branch 
turns  southwest  and  goes  up  the  main  Pequawket  Valley  for  somewhat 
more  than  2  miles,  when  it  again  parts  into  two  series,  one  of  which  goes 
nearly  south  over  a  high  hill  and  thence  to  Porter  Village,  while  the  other 
ascends  a  hill  toward  the  southeast  and,  when  near  the  top  of  a  pass  situ- 
ated at  the  northern  base  of  Pine  Hill,  imites  with  the  series  which  follows 
the  south  branch  of  the  Pequawket  Stream.  The  united  series  now  con- 
tinues southeast  through  the  pass  and  descends  180  feet  into  a  valley  open- 
ing eastwai'd.  By  following  down  a  rather  steep  slo^ie  in  this  valley  the 
glacial  river  might,  within  2  miles,  reach  the  very  large  glacial  river  which 
flowed  southwest  from  East  Brownfield  to  Kezar  Falls  along  the  valley  of 
Tenmile  River  and  through  the  remarkable  valley  in  the  western  part 
of  Hiram  called  The  Notch.  Instead,  it  ttn-ned  at  a  right  angle  southward 
and  climbed  a  hill  180  feet  high.  On  the  top  of  this  hill  the  river  was  in 
a  situation  interesting  to  study.  Right  in  fi'ont  of  it  is  a  valley  leading 
southeast  into  The  Notch,  and  by  taking  this  route  the  glacial  stream  might, 
within  2  miles,  have  joined  the  glacial  river  just  mentioned  at  a  point  250 
feet  or  more  lower  than  its  position  on  the  hilltop.  Instead  of  following 
this  valley  along  a  down  slope,  the  glacial  river  turned  southwest,  and  for 
an  eighth  of  a  mile  flowed  directly  on  the  top  of  the  ridge,  and  then  crossed 
a  north-and-south  hill  over  a  col  30  feet  high.  The  gravels  are  somewhat 
discontinuous  south  of  this  point,  but  can  readily  be  traced  along  the 
western  slopes  of  this  hill  to  Kezar  Falls. 

The  above  description  applies  to  an  area  only  about  10  miles  long 
from  north  to  south.  A  minute  description  of  the  branchings  and  reticula- 
tions and  other  developments  of  the  Saco-Mousam  network  of  gravel  plains 
must  be  omitted. 

But  there  is  one  line  of  gravels  that  demands  further  notice.  The 
Notch,  in  the  western  part  of  Hiram,  is  a  very  low  valley  with  U-shaped 
cross  section.  The  level  portion  at  the  bottom  is  usually  not  more  than 
one-fourth  of  a  mile  in  breadth,  and  at  the  highest  part  of  the  pass  it  is 
hardly  an  eighth  of  a  mile  wide.  From  this  point  two  streams  flow  in 
opposite  directions.  One  of  them  is  a  branch  of  Tenmile  River,  and 
flows  northeastward  into  the  Saco  River;  the  other  flows  southwestward 


260  GLACIAL  GRAVELS  OF  MAINE. 

into  the  Great  Ossipee  River  near  Kezar  Falls.  A  line  of  glacial  gravels 
extends  from  East  Brownfield  along-  The  Notch  to  Kezar  Falls.  In  the 
midst  of  The  Notch  are  three  ponds  bordered  by  plains  of  glacial  gravel 
rising  up  to  20  or  more  feet  above  the  water.  It  is  difficult  to  account 
for  lake  basins  being  excavated  by  boiHng  springs  in  a  mass  of  coarse 
composition  such  as  gravel,  cobbles,  and  bowlderets.  These  lake  basins 
must  have  been  deposited  in  substantially  their  present  shapes  by  the 
glacial  river.  This  is  an  interesting  divergence  from  the  ordinary  type 
of  osar-plain.  Here,  as  in  numerous  other  places,  we  find  the  broad  osar 
and  the  tracts  of  reticulated  ridges  passing  into  each  other  by  degrees. 

I  shall  sum  up,  briefly,  some  of  the  general  features  of  the  glacial 
gravels  of  this  region. 

Seldom,  and  then  only  for  a  short  distance,  do  the  gravels  take  the 
form  of  a  single  ridge  with  arched  cross  section,  like  the  osars  of  eastern 
Maine.  Toward  the  north  these  gravels  usually  take  the  form  of  a  broad 
osar,  i.  e.,  a  rather  level-topped  plain  from  a  few  rods  up  to  one-fourth  or, 
in  a  few  cases,  one-half  mile  wide.  Farther  south,  at  elevations  below  600 
and  above  230  feet,  the  gravels  expand  into  plains  of  reticulated  kame 
ridges  up  to  3  or  4  miles  in  breadth.  At  about  230  feet  the  reticulated 
kames  pass  into  the  great  level  delta-plains.  These  show  clearly  the  hori- 
zontal classification  of  sediments  characteristic  of  deltas,  and  sand  plains 
pass  by  degrees  into  marine  clays.  Here  and  there  small  delta  plains  are 
found  in  the  courses  of  both  osars  and  reticulated  kame  plains.  Many  of 
these  are  far  above  the  contour  of  230  feet  and  were  probably  deposited 
in  glacial  lakes. 

One  who  studies  the  glacial  gravels  only  on  southern  slopes  where  the 
rivers  now  flow  in  the  same  direction  and  in  the  same  valleys  as  the  glacial 
rivers,  will  find  it  difficult  to  distinguish  between  the  sediments  of  the  two 
kinds  of  rivers  in  such  situations.  He  may  come  to  attribute  all  the  allu- 
vium to  the  rivers  of  the  so-called  Champlain  period,  and  may  even  doubt 
the  existence  of  glacial  rivers,  at  least  as  agents  for  depositing  alluvium  so 
much  resembling  fluviatile  drift.  Such  skepticism  will  be  permanently 
removed  by  a  few  days  of  exploration  in  the  region  now  under  considera- 
tion. Here  he  will  see  these  long  lines  of  sand,  gravel,  and  coarser  sedi- 
ment go  up  and  over  the  steep  hills.  Here  can  be  seen  how  often  they 
reject  valleys  of  natural  di-ainage  and  instead  climb  hills  200  feet  or  more 


COMPLEX  IN  YORK  AND  OXFORD  COUNTIES.  261 

high,  leavmg  vast  deposits  of  water-assorted  matter  on  hillsides  where  there 
never  could  be  any  running  water  except  rain- water  rills  (see  PI.  XXII). 
Here  these  gravel  plains  divide  into  diverging  series  which  after  a  time  come 
together  again.  By  the  time  the  observer  has  seen  all  this  he  will  be  ready' 
to  admit  that  these  gravels  are  wholly  inexplicable  as  the  result  of  fluvia- 
tile,  lacustrine,  or  marine  action.  In  the  midst  of  these  winding  valleys  bor- 
dered by  high  hills  and  covered  by  water-rounded  cobbles,  bowlderets,  and 
bowlders,  showing  the  action  of  swift  currents  from  the  north,  and  in  .pres- 
ence of  the  meandering  lines  of  gravel,  wandering'  about  on  the  tops  of 
hills,  the  iceberg  theory  of  the  glacial  drift  of  Maine  utterlj'  breaks  down. 
These  circuitous  gravel  systems  bearing  such  curious  topographical  rela- 
tions become  of  themselves  one  of  the  strongest  proofs  of  the  existence  of 
the  ice-sheet  over  Maine.  Glacial  ice  accounts  for  the  barriers  necessarj' 
to  force  streams  over  hills  and  to  prevent  them  from  flowing  downhill  by 
the  steepest  slopes.  No  other  known  drift  agency  can  do  this.  The  critical 
student  of  the  great  northern  drift  should  by  all  means  visit  this  region. 

On  the  map  the  glacial  gravel  of  this  region  is  marked  as  ending  on 
the  north  a  short  distance  southeast  of  Fryeburg  Village.  North  of  this 
point  lies  the  large  level  "basin  of  Fryeburg,  Lovell,  Stowe,  and  Stoneham, 
inclosed  by  high  hills.  To  the  west  and  northwest  lie  the  White  Mountains 
and  their  outlying  ranges.  During  the  last  days  of  the  ice  this  level  valley 
would  be  filled  by  a  sort  of  local  glacier,  replenished  from  the  north  and 
west  along  valleys  where  the  flow  of  tlie  ice  could  continue  after  the  move- 
ment over  and  across  the  hills  lying  to  the  north  had  ceased.  Here  would 
be  a  local  tongue  of  ice  filling  a  valley  about  25  miles  long  and  from  3  to 
5  miles  broad.  In  all  this  valley  I  have  not  found  a  deposit  of  unmistak- 
able glacial  gravel.  Cold  River  originates  among  the  eastern  spurs  of  the 
White  Mountains  and  flows  southeastward  into  the  Saco  River.  Its  valley 
would  be  a  favorable  place  for  a  glacial  stream,  but  the  alluvium  in  the 
valley  is  very  different  from  the  gravel  here  described  as  glacial.  The 
stones  are  subangular  and  the  drift  is  clearlj^  fluviatile.  The  apparent 
absence  of  glacial  gravel  from  the  level  Fryeburg  basin,  while  it  is  so 
abundant  in  the  hilly  country  to  the  south,  will  be  further  discussed  in  a 
subsequent  chapter. 

South  and  east  of  the  Portland  and  Rochester  Railroad  the  country 
was  wholly  under  the  sea  as  far  as  the  New  Hampshire  line,  except  a  few 


262  GLACIAL  GRAVELS  OF  MAINE. 

ranges  of  hills  which  then  formed  islands.  A  large  part  of  the  sands  and 
gravels  of  this  region  were  deposited  in  the  sea,  mostly  in  the  open  sea  in 
front  of  the  ice,  but  in  part  in  broad  channels  opening  on  the  sea-like  bays 
inclosed  at  the  sides  by  ice.  In  this  region  the  gravels  are  somewhat  dis- 
continuous, and  mau}^  of  the  smaller  deposits  are  more  or  less  covered  by 
the  marine  clays;  they  are  therefore  difficult  to  trace.  I  have  only  partially 
explored  the  southern  portion  of  York  County. 

ACTON-NORTH    BERWICK    SYSTEM. 

This  series  of  gravels  is  provisionally  described  as  a  distinct  system, 
though  this  glacial  river  ma}^  have  joined  that  which  flowed  down  the 
Mousam  Valley.  If  so,  it  was  earl}-  in  the  Ice  age,  and  late  in  that  period 
these  streams  poured  into  the  sea  by  widely  separated  mouths.  The  system 
begins  about  a  mile  north  of  South  Acton,  on  the  southern  slope  of  a  high 
hill.  For  about  2  miles  it  consists  of  two  nearly  parallel  series  situated 
about  one-fourth  of  a  mile  apart.  One  of  them  is  a  series  of  short  ridges 
and  hummocks,  forming  a  single  line  like  the  osars,  with  only  a  few  out- 
lying and  reticulated  ridges.  These  gravels  run  southeast  across  the  valley 
of  a  stream  which  flows  eastward  into  the  Mousam  River.  It  then  pene- 
trates a  narrow  pass  through  the  hills  southward  over  a  divide  not  more 
than  50  feet  high.  In  this  pass  a  small  stream  soon  appears,  which  flows 
southward  past  East  Lebanon,  and  the  gravel  system  follows  the  same  val- 
ley, most  of  the  way  as  a  narrow  osar-plain,  now  much  eroded  by  the 
stream.  It  passes  near  Lebanon  station  of  the  Portland  and  Rochester 
Railroad  and  about  a  half  mile  west  of  Bauneg  Beg  Mountain,  and  con- 
tinues south  and  east  through  North  Berwick  into  Wells.  As  already 
stated,  the  system  near  South  Acton  is  double.  The  more  western  gravels 
begin  near  the  other  series,  but  keep  about  100  feet  above  it  on  the  hillside. 
They  take  the  form  of  a  small  two-sided  ridge  or  osar  with  very  steep  lat- 
eral slopes  and  a  very  meandering  course.  The  material  is  but  little  water- 
worn.  Within  about  2  miles  it  comes  down  the  hill  to  near  the  other  series 
in  the  valley,  and  is  then  lost.  No  doubt  it  was  deposited  by  a  small  tribu- 
tary of  the  main  glacial  river.  This  little  osar-ridge  is  situated  400  feet  or 
more  above  the  sea,  and  the  difference  between  its  steep  side  slopes  and  the 
low  arch  of  the  ridges  found  below  230  feet  is  very  noticeable. 

From  East  Lebanon  southward  this  system  traverses  a  gently  rolling 


PLEXUS   OF    KAME    RIDGES   AND    MOUNDS;    NEAR    NORTH    ACTON. 


B.     TERMINAL   MORAINE;   WINSLOWS   MILLS,   WALDOBORO. 


LEBANON  AND  WEST  LEBANON  SYSTEMS.  263 

plain.  Here  and  there  are  readies  of  level  osar-plain,  but  for  most  of 
this  distance  the  gravel  takes  the  form  of  a  plain  of  reticulated  kames 
one-eighth  of  a  mile  or  more  wide.  The  system  passes  not  far  west  of 
Bauneg  Beg  Mountain,  and  expands  into  a  marine  delta  not  far  north  of 
North  Berwick  Village.  South  and  east  of  this  point  are  some  discon- 
tinuous plains  of  sand  and  gravel,  but  their  connections  are  obscure. 
Maryland  Ridge,  in  Wells,  is  a  large  and  broad  ridge  of  glacial  gravel 
having-  a  southeast  direction.  I  provisionally  mark  it  as  a  part  of  this 
system,  though  possibly  connected  with  the  great  series  that  extends  from 
Conway  and  the  Ossipee  Lake  region,  in  New  Hampshire,  down  the 
Mousam  Valley  past  Sauford. 

LEBANON    SYSTEM. 

A  series  of  somewhat  discontinuous  and  plain-like  gravels  extends 
from  near  Wentworth  or  Northeast  Pond,  and  in  the  northwestern  part 
of  Lebanon,  southward  through  the  central  part  of  Lebanon,  following  a 
rather  low  pass  and  then  the  valley  of  a  stream  that  passes  near  South 
Lebanon.  Toward  the  south  there  are  several  narrow  plains,  which 
diverge  in  direction,  as  if  delta  branches  of  this  system.  These  have  been 
traced  by  me  only  a  short  distance  into  Berwick.  I  am  indebted  to  Mr. 
J.  H.  Hammond,  of  Sanford,  for  much  information  regarding  this  portion 
of  York  Comity. 

WEST  LEBANON  SYSTEM. 

This  gravel  system  begins  on  the  east  side  of  Salmon  Falls  River  a 
mile  or  two  north  of  East  Rochester.  It  crosses  into  New  Hampshire  near 
East  Rochester,  and  is  said  to  extend  to  Dover,  New  Hampshire. 


CHAPTER    V 


CLASSIFICATION   AND   GENESIS. 

Althougn  we  need  not  now  study  the  causes  of  such  astonishing  vari- 
ations in  climate  as  have  taken  place  in  post-Tertiaiy  time,  we  must  assume 
an  ice-sheet  covering  all  New  England  except  perhaps  a  few  of  the  highest 
peaks.  For  the  present  we  must  investigate  the  order  of  events.  The 
higher  questions  invohang  the  causes  of  geological  climates  must  come 
later.  As  it  is  the  first  office  of  science  to  classify  facts  and  discover  their 
underlying  principles,  it  remains  for  us  to  make  a  detailed  examination  of 
the  known  facts  and,  if  possible,  to  reach  a  satisfactory  classification  and 
explanation  of-  them.  The  moment  we  enter  upon  this  inquiry,  however, 
we  confront  the  difficulty  of  isolating  the  glacial  sediments  from  the  other 
glacial  deposits  or  from  other  forms  of  water  transportation,  and  our  subject 
at  once  broadens  so  as  to  include  every  form  of  superficial  deposit. 

Probably  northern  Greenland  typifies  more  nearly  than  any  other 
known  country  the  condition  of  New  England  at  the  time  it  was  covered 
by  ice.  It  is  known  that  the  interior  of  that  country  is  covered  b}'  a  great 
continuous  snow  field  that  rises  above  all  the  hills  and  most  of  the  moun- 
tains and  is  discharged  into  the  sea  by  broad  glaciers.  During  the  greater 
part  of  the  Ice  age  the  glaciers  of  New  England  were  practically  confluent. 
The  ice  then  extended  far  out  into  the  present  Gulf  of  Maine,  and  was  there 
discharged  into  the  ocean  as  icebergs  or  as  melting  waters.  The  drift 
which  Avas  at  that  time  deposited  near  the  ice  front  is  now  beneath  the 
Atlantic.  But  the  last  part  of  the  Glacial  period  saw  the  extremity  of  the 
retreating  ice  confronted  by  the  sea  along  a  very  crooked  line  situated  over 
what  is  now  the  dry  land.  The  sea  then  stood  at  about  230  feet  above  its 
present  level,  and  broad  arms  of  salt  water  extended  far  into  the  interior  of 
the  State  along  the  principal  valleys.     Our  problem  involves  both  the  study 


PEEGLACIAL  LAND  SURFACE  AND  SOILS.  265 

of  the  geological  work  of  the  ice  on  the  land  of  that  period  and  also  the 
offshore  drift  then  thrown  into  the  ocean  by  the  ice-sheet  itself,  by  ice  floes 
and  icebergs,  and  by  glacial  rivers,  the  whole  having  since  been  more  or 
less  modified  by  the  waves  and  currents  of  the  sea.  The  subsequent 
retreat  of  the  sea  to  its  present  position  has  exposed'  these  deposits  for 
convenient  study,  and  thus  has  furnished  a  good  example  of  the  multi- 
foi'm  work  going  on  off  an  ice-bound  coast.  Our  geological  conceptions 
are  thus  enlarged  by  the  same  process  that  added  the  claj"  loams  to  the  list 
of  the  soils  of  Maine.  But  the  problem  before  us  involves  more.  The 
final  melting  of  the  ice  over  the  land  left  the  waters  free  to  follow  the  val- 
leys of  natural  drainage.  Rivers  much  larger  than  the  present  rivers  then 
flowed  into  the  sea  from  30  to  100  miles  above  their  present  mouths  and 
were  depositing  deltas  in  the  sea  not  far  from  the  coast  line  as  it  at  that 
time  existed.  These  deltas  are  now  exposed  for  our  study,  and  are  to  be 
distinguished  from  marine  and  glacial  sediments.  Moreover,  before  the  ice 
had  all  melted,  lakes  gathered  on  the  land,  confined  wholly  or  in  part  by 
ice.  Thus  the  various  kinds  of  drift  of  the  glacier  are  to  be  distinguished 
in  the  midst  of  preglacial  soils  and  lacustrine,  fluviatile,  and  mai-ine  sedi- 
ments, often  since  modified  by  the  action  of  the  wind  and  streams,  or 
strewn  by  drift  from  floating  ice,  or  eroded  in  part  and  carried  away  beyond 
our  sight,  or  bodily  misplaced  by  landslips.  Everything  whicli  directly  or 
indirectly  produced  a  single  one  of  the  field  phenomena  must  be  of 
interest  to  us. 

PREGIiACIAIj   LAND   SURFACE  AND   SOILS. 

The  longer  a  region  has  been  above  the  sea  the  more  nearly  are  the 
surface  features  due  to  upheaval  and  unequal  elevation  replaced  by  those 
due  to  subaerial  erosion.  The  coming  of  the  ice-sheet  found  Maine  in  that 
stage  of  development  called  geological  "old  age."  The  land  had  been 
deeply  sculptured,  here  with  a  heavy  stroke,  there  with  a  lighter  touch,  and 
the  rock  yielded  in  different  degrees  to  the  attack  of  the  chisel.  Only  the 
ruins  of  the  folds  and  cones  produced  by  mountain-making  forces  remained. 
The  outlines  of  these  remnants  of  a  primeval  land  were  about  like  the 
present  surface  forms  of  the  State,  save  that  the  hills  were  more  roug'li  and 
angular  in  outline.  Steep  cliffs  of  erosion  abounded  which  were  ragged 
with  weather-rounded  bowlders.     The   long  conflict  which  for  a^eological 


266  GLACIAL  GRAVELS  OF  MAmE. 

eons  had  been  going  on  between  the  elements  and  the  living  rock  was 
testified  to  by  the  towers  and  buttresses  with  which  the  rock  in  vain ' 
strengthened  its  scarps  of  erosion.     While  the  outlines  of  the  hills  were  not 
so  beautifully  curved  as  at  present,  the  drainage  basins  and  the  relative 
height  of  hill  and  valley  were  probably  about  the  same. 

It  is  uncertain  to  what  depth  the  rock  had  become  weathered  in 
preglacial  time.  Over  the  driftless  area  of  Wisconsin  the  residual  earth 
has  been  found  by  Chamberlin  and  Salisbury  to  have  a  thickness  of  4 
feet.  In  a  region  of  granitic  rocks  the  residual  earth  represents  but  a  small 
part  of  the  rock  which  has  become  shattered  and  more  or  less  disintegrated. 
In  the  Blue  Ridge  of  Virginia  I  have  repeatedl}'-  seen  railroad  cuts  where 
the  Archean  schists  were  weathered  and  fi-actured  to  a  depth  of  20  to  30 
feet.  In  Maine  the  roofing  slates  weather  with  such  extreme  slowness  that 
the  preglacial  soil  may  have  been  on  the  average  only  a  few  inches  thick, 
and  the  weakened  rock  only  a  few  inches  more.  The  sedimentary  sand- 
stones, etc.,  may  have  had  only  about  the  same  depth  as  in  the  di'iftless 
area  of  Wisconsin,  but  the  crystalline  and  schistose  rocks  must  have  been 
weathered  to  a  much  greater  depth.  Many  of  the  feldspathic  rocks  have 
become  weathered  to  a  depth  of  several  inches  to  several  feet  in  postglacial 
time,  and  this  indicates  a  deep  preglacial  sheet  or  surface  layer  of  soil, 
subsoil,  and  bowlders  of  decomposition.  Obviously  the  actual  depth 
attained  depends  on  the  ratio  between  weathering  and  transportation.  The 
till  is  much  more  abundant  in  the  regions  of  schistose  rocks  than  in  those 
of  slates  and  sandstones.  This  of  itself  is  a  proof  of  a  g'reater  depth  of 
weakened  rock,  and  in  the  granitic  regions  there  was  a  still  greater  depth. 
Judging  by  the  cliffs  on  the  south  side  of  Russell  Mountain,  elsewhere 
described,  I  do  not  think  it  an  extravagant  estimate  that  the  rock  in  pre- 
glacial time  had  there  become  fractured  into  blocks  removable  by  the  ice 
to  a  depth  of  50  feet.  This  was  in  granite,  and  not  a  very  easily  weathering 
variety.  The  depth  of  rock  which  had  become  fractured  and  more  or  less 
weathered  in  preglacial  time  may  be  estimated  at  from  a  few  inches  up  to 
perhaps  50  feet. 

Since  the  land  had  been  for  a  long  time  above  the  sea,  the  larger 
valleys  would  have  attained  a  base-level  of  erosion.  Lakes  occupying  rock 
basins,  if  there  had  been  any,  would  have  been  silted  up  or  have  been 
drained  by  the  cutting  down  of  theii-  inclosing  barriers,  or  in  case  of  shallow 


PEEGLACIAL  LAiSTD  SURFACE  A^D  SOILS.  267 

basins  they  may  have  been  filled  with  peat.  In  the  valleys  there  would  be 
much  stream  wash — silts,  sands,  and  gravels.  I  have  never  g'iven  up  hope 
that  somewhere  portions  of  these  pi'eglacial  soils,  peats,  or  lake  sediments 
were  enabled  to  sur\ave  beneath  the  rough  ridings  of  the  ice-sheet  in  masses 
sufficiently  large  to  contain  characteristic  fossils  and  be  recognizable.  So 
far  as  yet  discovered,  the  only  bodies  of  preglacial  soil  that  failed  to 
be  incorporated  with  the  di'ift  of  the  ice-sheet  were  contained  in  small 
depressions  of  the  rock.  They  consist  mainly  of  rock  weathered  in  situ, 
and  plainly  underlie  the  glacial  drift.  They  are  much  the  oldest  of  the 
superficial  deposits  of  Maine.  The  largest  of  the  depressions  of  this  kind 
in  which  the  primeval  soils  are  preserved  were  in  argillitic  and  quartzitic 
schists,  and  were  less  than  7  feet  in  diameter,  unless  certain  narrow  east- 
west  ravines  in  sedimentary  rock  that  open  out  from  the  gorge  of  the 
Seboois  River  not  far  from  Mount  Katahdin  be  also  of  this  kind.  The  pro- 
jecting tongues  left  by  the  unequal  weathering  of  the  fine-grained  schists 
were  thin  and  easily  broken.  Hence  these  rocks  were  reduced  by  the 
glacier  to  such  an  even  or  gently  undulating  surface  that  their  glaciation 
may  well  be  tei'med  planing.  The  mica-  and  other  coarse  schists  yield  fewer 
areas  of  preglacial  weathering,  and  these  only  from  1  to  3  feet  in  diameter. 
The  laminse  are  thicker  and  vary  much  in  hardness.  The  glaciated  rock 
often  shows  undulations  a  few  inches  wide  and  from  1  to  3  inches  high,  so 
that  the  surface  has  a  ribbed  appearance,  as  of  corduroy.  The  projecting 
ribs  are  rather  parallel  to  the  strike  of  the  laminse  of  schists,  and  more  often 
are  transverse  to  the  glaciation.  Where  the  furrows  between  the  ridges  are 
very  large  they  have  sometimes  been  described  as  grooves  gouged  out  of 
the  rock  by  a  single  bowlder.  Where  they  happen  to  be  parallel  with  the 
glaciation  it  is  difficult  to  decide  the  question  of  their  origin;  but  where 
they  are  parallel  with  the  lamination  of  the  rock  and  transverse  to  the 
glaciation,  as  they  usually  are,  they  ixiust  be  regarded  as  due  to  the  condi- 
tion of  the  weathered  rock  as  the  ice  began  to  act  upon  it.  The  ridges  are 
the  projecting  edges  of  the  harder  layers  which  the  glacier  was  not  able  to 
plane  ofF  to  a  flat  surface,  although  removing  the  weakened  rock  and  leaving 
the  surface  of  both  the  ridges  and  the  hollows  thoroughly  polished,  In 
other  words,  in  these  cases  the  signs  of  the  surface  of  preglacial  weathei'ing 
were  not  entirely  obliterated. 

The  granites  and  syenitic  granites  are  glaciated  in  still  more  irregular 


268  GLACIAL  GRAVELS  OF  MAINE. 

surfaces.  They  show  greater  numbers  of  rounded  bosses,  or '  roches 
moutonn^es,  and  many  small  rock  basms.  These  depressions  are  glaciated 
even  to  the  bottom.  I  have  not  been  able  to  find  in  granite  areas  surfaces 
of  preglacial  Aveathering,  except  at  certain  cliffs  facing  the  south.  For 
instance,  at  the  southern  brow  of  Russell  Mountain,  in  Blanchard,  there  is  a 
steep  cliff  several  hundred  feet  in  height.  The  upper  portion  has  been 
shattered  by  the  elements  into  a  wall  of  bowlders  of  decomposition,  most 
of  them  still  occupying  their  original  relative  positions.  Some  of  the 
largest  of  the  upper  tier  of  bowlders  have  been  moved  several  feet  south- 
ward, so  as  almost  to  cause  them  to  fall  down  the  cliffs.  The  top  and 
northern  slopes  of  the  hill  are  intensel}^  glaciated,  and  they  so  far  bore  the 
brunt  of  the  attack  that  the  ice  only  partially  succeeded  in  pushing  these 
bowlders  from  their  places.  Doubtless  on  that  cliff  in  preglacial  time  there 
rested  many  a  bowlder  which  the  ice  was  afterwards  able  to  push  over  the 
brink  and  carry  away.  The  turrets  and  battlements  of  the  castle  as  the 
glacier  found  it  have  been  cut  off,  and  perhaps  the  upper  stories,  but 
enough  remains  to  remind  us  that  the  power  of  ice  has  some  limit. 

The  condition  of  the  surface  of  the  glaciated  rock  in  Maine  proves 
that  the  behavior  of  a  thin  glacier,  such  as  the  extremities  of  those  of 
Switzerland  and  Norway  to-day,  is  A'ery  different  from  that  of  one  a  half 
mile  or  more  in  thickness.  Under  the  deep  ice  of  the  time  of  maximum 
accumulation  only  here  and  there  a  small  depression  became  filled  by  sub- 
glacial  till  or  by  embayed  ice,  so  that  the  glacier  flowed  over  it  as  if  it  had 
been  solid  rock.  We  have  seen  that  the  bottoms  of  most  of  the  narrow 
furrows  were  glaciated  even  when  transverse  to  the  direction  of  the  motion. 
It  was  very  different  during  the  last  of  the  Grlacial  period,  when  the  ice  had 
become  thin.  Thus,  at  one  of  the  lime  quarries  at  Rockland,  in  a  north- 
east and  southwest  valley,  there  is  an  earlier  series  of  long,  straight 
scratches  bearing  S.  31°  W.  Later  scratches  are  found  which  in  places 
have  obliterated  the  earlier  ones.  They  bear  S.  51°  W.  The  smooth, 
even  surface  of  the  limestone  ledge  gently  inclines  southwestward  about 
1  foot  in  40.  On  this  incline  there  is  a  steeper  place  where  within  3  feet 
there  is  a  fall  of  3  or  4  inches.  The  later  scratches  come  up  to  the  northern 
edge  of  the  steeper  incline,  when  they  disappear  for  about  3  feet,  then  begin 
again  near  the  foot  of  the  steep  incline  and  continue  southward.  The 
steeper  slope  is  beautifully  glaciated,  but  the  scratches  were  made  during 


GEEENLAND  SNOW  AND  ICE.  269 

the' earlier  glaciation.  Here  at  the  time  the  later  scratches  were  made  the 
ice  could  not  bend  downward  so  sharply  as  the  small  change  in  direction  of 
slope.  In  other  words,  the  ice  traveled  3  feet  horizontally,  held  u]3  by  its 
cohesion,  before  it  would  bend  downward  3  inches.  On  the  other  hand, 
the  earlier  scratches  changed  instantly  with  the  slope,  and  they  themselves 
were  a  deflection  from  the  general  glaciation  of  the  region  in  which  they 
are  found,  and  probably  were  not  made  at  the  time  of  greater  thickness  of 
ice.  All  over  Maine  the  earlier  scratches  bend  sharply  (in  vertical  planes) 
around  curves  and  some  pretty  sharp  angles.  Such  facts  jjrove  th^t 
deductions  drawn  from  the  behavior  of  thin  glaciers  do  not  in  all  respects 
apply  to  thick  ones.  And  yet  if  a  thin  glacier  can  not  at  once  bend  its 
course  downward  under  the  force  of  gravity,  it  is  evident  that  the  same 
causes,  but  operating  under  different  circumstances,  will  limit  the  power  of 
even  a  great  ice-sheet  to  flow  down  into  cavities  and  glaciate  them.  The 
ice,  as  shown  elsewhere,  must  have  been  less  than  200  feet  thick  at  the 
time  of  the  formation  of  the  Waldoboro  moraine.  The  pressure  on  its  bed 
(neglecting  the  weight  of  moraine  stuff")  was  less  than  6  atmospheres.  If 
the  thickness  of  the  ice  over  Maine  was  only  half  a  mile,  the  ^jressure  at  the 
base  was  at  least  84  atmospheres.  Under  this  enormous  pressure  the 
power  of  the  ice  to  flow  down  into  hollows  was  very  great,  but  not  unlim- 
ited. Here  and  there  a  small  portion  of  that  ancient  surface  was  protected 
by  a  curve  of  the  rock. 

GREENLAND   SNOW  AND  ICE. 

The  only  region  sufficiently  explored  to  enable  us  to  identify  its  con- 
dition with  that  of  northern  New  England  in  the  time  of  the  ice-sheet  is 
Greenland.  Most  of  what  we  know  of  the  condition  of  the  interior  is  due 
to  the  labors  of  the  Danish  geologists,  of  Torell,  Nordenskjold,  and  Hoist 
of  Sweden,  of  Lieut  R.  E.  Peary  of  the  United  States  Navy,  and  others. 

The  principal  facts  relative  to  the  ice  and  snow  of  Greenland  likely  to 
be  of  use  to  us  in  the  interpretation  of  the  facts  as  exhibited  in  Maine  are 
the  following: 

The  eastern  coast  is  bordered  by  much  shore  ice.  Near  the  southern 
extremity  the  country  is  mountainous,  and  numerous  glaciers  occupy  the 
interior,  but  none  reach  the  sea.  Going  north  the  inland  ice  descends  lower 
and  the  principal  fiords  serve  as  the  outlet  of  glaciers,  which  come  down 


270  GLACIAL  GEAYELS  OF  MAIJfE. 

to  the  sea  level  and  end  in  cliffs  near  tlie  heads  of  the  fiords,  where  the  ice 
breaks  off  as  icebergs.  Still  farther  north  these  glaciers  extend  out  nearly 
to  the  mouths  of  the  fiords,  and  they  become  broader.  Finally  the  glaciers 
become  confluent  in  great  ice-sheets  that  confront  the  sea  in  a  solid  and 
continuous  wall  for  a  hundred  miles  or  more.  Part  of  this  great  breadth  is 
due  to  the  climate,  part,  perhaps,  is  due  to  the  form  of  land  surface.  Going 
from  the  coast  inland  we  find  the  ice  surface  rapidly  rising.  Near  the  shore 
the  ice  usually  barely  fills  the  valleys,  leaving  the  mountains  bare.  Inland 
only  a  short  distance,  we  find  but  few  peaks  (nunatakker)  projecting 
above  the  ice.  Within  30  or  60  miles  we  reach  a  i-egion  where  even  the 
highest  peaks  are  wholly  beneath  a  great  continuous  ice-and-snow  field. 
In  the  interior  no  moraine  stuff  appears  on  the  surface  of  the  ice,  though 
there  is  more  or  less  dust,  the  kryokonite  of  Nordenskjold.  Some  moraiual 
matter  falls  from  the  nunatakker  onto  the  ice  as  we  approach  nearer  the 
margin,  but  near  the  extremity  many  stones  and  bowlders  appear  on  the 
surface.  Many  of  these  are  in  situations  where  they  are  supposed  not  to 
have  fallen  on  the  surface  from  nunatakker,  but  have  got  up  into  the  ice 
from  below,  and  were  subsequently  exposed  by  the  melting  of  the  ice  or 
b}'  movements  ■\A'itlnn  the  ice.  These  are  glaciated  little  or  not  at  all.  In 
several  places  the  Danish  geologists  have  seen  a  ground  moraine,  as,  for 
instance,  where  a  thin  flow  of  ice  takes  place  over  the  cols  between  two  or 
more  nunatakker  while  the  deep  mass  divides  and  flows  aroimd  them.  The 
two  main  streams  unite  a  short  distance  below  the  bui-ied  ridge.  In  lee  of 
the  buried  ridge  a  moraine  is  formed,  brought  over  by  the  thin  sheet.  The 
material  of  this  moraine  is  intensely  glaciated.  In  some  cases  a  moraine 
profonde  has  been  seen  beneath  the  ice  near  its  extremity.^ 

THE  TILL. 

While  in  general  the  unmodified  glacial  drift,  or  till,  rests  upon  the 
preglacial  soils  and  the  glaciated  rock,  yet  there  are  local  exceptions  where 
a  later  deposit  rests  on  the  rock  in  consequence  of  the  absence  of  till  or 
the  occurrence  of  landslips.  Indeed,  landslips  have  been  so  common  that 
it  is  unsafe  to  trust  any  inferences  as  to  the  chronological  order  of  events 

'  This  account  is  condensed  from  tlie  above-mentioned  authors,  quoted  by  J.  E.  Marr  in  Geol. 
Mag.,  April,  1887. 

Since  the  above  was  written  a  paper  on  Hoist's  observations  in  Greenland  has  been  published 
in  the  American  Naturalist  (July  and  August,  1888),  by  Dr.  J.  Lindahl. 


THE  TILL.  271 

until  it  is  clearly  proved  that  there  have  been  no  slides  at  the  places  of 
observation. 

A  fundamental  question  regarding  the  till  relates  to  its  origin.  The 
hypothesis  of  Torell — that  part  of  the  morainal  matter  of  the  ice-sheet  was 
beneath  the  ice,  while  the  upper  portion  was  distributed  through  the  lower 
part  of  the  ice — has  since  1877  appeared  to  me  to  explain  satifactorily  the 
facts  as  observed  in  Maine.  The  principal  considerations  bearing  on  the 
subject  are  the  following: 

We  do  not  know  how  the  age  of  ice  began.  Looking-  at  it  from  the 
standpoint  of  our  present  climatic  conditions,  it  would  most  naturally  come 
on  gradually.  After  a  time  local  glaciers  filled  the  mountain  valleys. 
Above  them  rose  cliffs  that  had  been  rent  into  loose  blocks  during  the  long 
ages  preceding.  Much  of  this  cliff  debris  fell  down  upon  the  ice  and 
formed  moraines  like  those  of  the  Alpine  glaciers.  But  more  snow  con- 
tinued to  fall  than  melted,  and  the  time  came  when  this  morainal  matter 
and  the  hills  were  overtopped  by  the  snow  and  ice.  Unless  the  higher 
peaks  of  the  White  Mountains  and  Mount  Katahdin  be  exceptions,  all  tlie 
territory  was  covered.  The  proof  of  this  is  conclusive,  since  the  rocks  on 
the  hills  are  scored  and  afford  drift  bowlders  transported  from  the  north. 

So,  too,  during  the  decadence  of  the  ice-sheet  the  tops  of  the  higher 
hills  appeared  above  the  ice  long  before  the  flow  in  the  valleys  ceased.  The 
glacier  had  just  swept  over  the  cliffs  and  removed  most  of  the  talus  and 
bowlders  of  decomposition;  few  therefore  would  fall  upon  the  ice.  The 
melting  of  the  upper  portions  of  the  ice  would  leave  many  bowlders  on 
the  higher  and  steeper  parts  of  the  hills  in  such  unstable  equilibrium  that 
now  and  then,  as  one  was  freed  from  the  embrace  of  the  ice,  it  would  roll 
or  slide  down  the  slopes  onto  the  ice  that  still  remained  in  the  lower  parts 
of  the  valleys.  At  this  time  landslides  of  the  freshl}^  deposited  material 
would  naturally  be  frequent.  In  these  ways  it  ma}^  be  admitted  as  possible 
that  morainal  matter  was  at  this  period  precipitated  from  above  upon  the 
ice,  after  the  manner  of  ordinary  valley  glaciers.  But  if  moraines  were 
thus  accumulated  we  ought  now  to  find  them,  in  the  form  of  ridges  and 
trains  of  bowlders,  especially  at  the  flanks  of  the  high,  steep  hills.  On 
the  contrary,  the  bowlder  trains  are  in  lee  of  granite  knobs,  where  a  cliff 
was  shattered  beneath  the  ice  and  its  bowlders  pushed  forward.  While, 
then,  we  may  grant  a  limited  fall  of  debris  from  above  onto  the  top  of  the 


272  GLACIAL  GEAVELS  OF  MAINE. 

ice  during  the  beginning  and  near  the  end  of  the  existence  of  the  ice-sheet, 
yet  this  supposed  moraine  stuff  is  not  now  so  distinctly  arranged  in  the 
form  of  medial  or  lateral  moraines  as  to  warrant  the  assertion  that  any 
considerable  amount  ever  fell  upon  the  ice  from  above.  And  it  is  therefore 
practically  self-evident  that  during  the  time  when  all  the  country  was  cov- 
ered with  ice  the  morainal  matter  could  get  into  the  ice  only  from  beneath. 

MORAINAL  DEBRIS   OF   THE   ICE-SHEET. 
MORAINE   STUFF   IN   THE   LOWER   PART   OF   THE   ICE. 

That  till  matter  had  in  some  way  worked  up  into  the  lower  part  of  the 
ice  is  conclusively  proved  by  the  presence  of  several  terminal  moraines. 

WALDOBORO   MORAINE. 

■  The  largest  of  these  terminal  moraines  extends  from  near  Winslows 
Mills,  Waldoboro,  for  about  6  miles  north  and  eastward.  Its  general 
appearance  is  that  of  a  two-sided  ridge,  or  sometimes  of-  two  or  three 
roughly  parallel  ridges.  It  is  composed  of  the  same  kind  of  matter  as  the 
upper  layers  of  the  till,  of  the  surrounding  region,  unless  perhaps  it  has  had 
a  small  proportion  of  the  finest  rock  flour  washed  out  of  it  by  very  gentle 
currents. 

Regarding  this  moraine  it  may  be  said: 

1.  The  moraine  is  not  composed  of  matter  torn  up  from  the  ground 
moraine  or  previously  deposited  till  and  pushed  forward  by  the  snout  of 
an  advancing  glacier.  As  elsewhere  recorded,  a  series  of  hummocks  and 
short  ridges  of  glacial  gravel  extends  from  Waldoboro  northward  along  the 
Medomac  Valley  to  a  point  more  than  a  mile  north  of  the  moraine.  One 
mound  of  this  series  directly  underlies  the  more  northern  of  the  two  ridges 
at  Winslows  Mills.  If  the  ice  during  an  advance  had  been  able  to  push 
before  it  so  large  a  ridge  composed  of  till  previously  laid  down  on  the  bare 
earth,  it  ought  to  be  able  to  push  before  it  the  heap  of  glacial  gravel  now 
found  beneath  the  moraine,  as  well  as  all  the  other  eskers  situated  north  of 
this  point.  But  no  esker  material  appears  in  the  moraine — only  ordinary, 
slightly  water-washed  till.  Also,  the  external  forms  of  the  eskers  north  of 
the  moraine  differ  little  if  any  from  those  situated  south  of  it,  so  far  as  I 
could  discover. 


A      SECTION    OF   TERMINAL    MORAINE 


B.     TOP   OF    TERMINAL   MORAINE. 


WALDOBORO  MORAINE.  273 

2.  During  the  gradual  shrinking  of  a  glacier  no  frontal  morainal  ridge 
can  be  formed.  The  morainal  matter  is  left  scattered  promiscuously  over 
the  field  of  retreat. 

3.  When  the  rate  of  flow  of  the  ice  equals  or  nearly  equals  the  rate  of 
melting  at  the  ice  front,  a  rather  steep  ridge  must  form  at  the  end  of  the 
glacier. 

It  thus  appears  reasonably  certain  that  the  Waldoboro  moraine  was 
not  formed  during  an  advance  or  recession  of  the  extremity  of  the  ice,  but 
during  a  time  when  the  rate  of  advance  or  flow  of  the  ice  at  that  point  very 
nearly  equaled  its  rate  of  melting-.  South  of  Winslows  I  have  found  no 
similar  ridge.  It  is  a  fair  inference  that  during  the  time  previous  to  the 
period  of  this  frontal  moraine  the  ice  had  been  melting  faster  than  it  was 
reijlenished  by  flowing'  ice  from  the  north.  Here  for  a  time  the  two  rates 
were  nearly  equal,  allowing,  however,  for  two  or  three  little  periods  when 
the  ice  receded  a  few  rods  and  then  held  its  own  again.  Then  the  rate  of 
melting  gained  on  the  rate  of  ice  flow,  and  as  the  front  retreated  northward 
the  country  was  covered  with  a  diffused  sheet  of  till. 

To  the  north  of  this  moraine  lies  a  gently  rolling  plain  for  a  few  miles, 
and  then  we  come  to  a  range  of  round-topped  hills  rising  500  to  800  feet 
above  the  sea.  This  plain  would  be  leather  favorable  to  the  flow  of  ice  south- 
ward up  to  a  very  late  date.  The  moraine  crosses  several  hills.  Its  highest 
point  is  about  150  feet  above  tide  water.  At  this  point  it  crosses  the  north- 
ern spur  of  a  hill  which  toward  the  south  rises  near  a  hundred  feet  higher  than 
the  moraine.  If  the  ice  had  much  exceeded  150  feet  in  thickness,  it  ought 
to  have  reached  a  higher  point  on  the  hill  than  it  did.^  If  we  assume  a 
thickness  of  less  than  200  feet  of  ice  at  the  time  of  the  formation  of  the 
moraine,  we  must  admit  that  it  is  probable  the  higher  hills  of  "Washing- 
ton and  Liberty,  situated  north  of  this  place,  rose  above  the  surface  of 
the  ice  at  that  time.  If  moraines  then  formed  on  the  ice  from  matter  slid- 
ing down  from  the  hills,  we  ought  now  to  find  lateral  moraines  bordering 
the  valleys  that  lie  between  these  hills,  and  thence  extending  south  to  the 


'  Observations  in  Greeulaad  and  by  Eussell  in  Alaska  prove  that  when  a  rock  or  hill  rises  in  the 
midst  of  a  glacier  the  ice  is  driven  far  up  the  stoss  side  of  the  obstruction,  sometimes  to  a  height  of 
several  hundred  feet.  If  this  sort  of  action  took  place  at  the  hill  crossed  by  the  moraine  east  of 
Winslows  Mills,  the  thickness  of  the  ice  may  have  been  even  less  than  the  above  estimate.  The  ice 
did  not  reach  so  far  south  on  the  hillside  by  an  eighth  of  a  mile  or  more  as  it  did  in  the  valleys  situ- 
ated east  and  west  of  the  hill.  This,  perhaps,  may  prove  that  the  ice  over  the  ,hill  dragged  behind 
the  deeper  ice  of  the  valleys  because  it  there  bulged  somewhat  above  the  general  level  of  the  surface. 
MON  XXXIV 18 


274  GLACIAL  GRAVELS  OF  MAINE. 

Waldoboi'O  moraine.  The  phenomenon  of  crag  and  tail  is  very  common 
in  those  parts,  but  I  have  discovered  no  lateral  or  medial  moraines  proper 
in  any  of  the  larger  valleys,  and  I  have  crossed  them  all.  The  liills  are 
not  precipitous  nor  very  steep,  at  least  they  do  not  jjrove  so  to  the  Maine 
farmer  who  has  much  of  their  surface  under  cultivation.  These  conditions 
naake  it  improbable  that  any  considerable  amount  of  morainal  matter  got 
upon  the  ice  by  sliding  from  the  hilltops  at  the  time  the  hills  were  bare  and 
glaciers  still  filled  the  vallej^s. 

The  argument,  then,  stands  thus :  The  moraine  is  not  composed  of  pre- 
viously deposited  till  plowed  up  and  pushed  l^efore  it  by  the  snout  of  the 
glacier.  Neither  can  it  contain  much  if  anv  matter  precipitated  upon  the 
ice  from  above.  It  is  a  fair  inference  that  the  moraine  consists  chiefly  or 
wholly  of  matter  which  had  previously  g'ot  up  into  the  lower  part  of  the 
ice  from  below.  A  part  of  it  may  have  been  on  the  surface  of  the  ice  at 
the  time  the  moraine  was  being  formed,  but  if  so  it  was  because  it  had  been 
laid  bare  by  the  melting  of  the  ice  above  it.  The  composition  of  the 
moraine  proves  that  debris  of  all  degrees  of  fineness,  from  the  finest  clay 
and  dust  up  to  the  largest  bowlders,  were  contained  in  the  lower  part  of  the 
ice.  True,  the  moraine  at  the  excavations  near  Winslows  Mills  is  some- 
what more  sandy  than  the  average  upper  till  of  the  locality,  but  this  can  be 
easily  accounted  for  if  we  assume  that  it  was  deposited  in  the  sea  at  the 
front  of  the  ice,  or  became  somewhat  water  washed  by  the  terminal  melting. 
Only  a  few  of  the  stones  of  the  moraine  are  distinctly  scratched,  in  which 
re^spect  they  are  like  the  stones  of  the  upper  part  of  the  till.  In  a  word, 
the  material  is  the  same  as  found  in  the  upper  portion  of  the  till  of  that 
region.  The  structural  difference  consists  in  the  fact  that  we  have  here 
piled  in  a  single  ridge  material  which  during  a  gradual  recession  of  the  ice 
front  would  be  scattered  as  a  sheet  over  a  zone  a  half  mile,  more  or  less,  in 
breadth. 

MORAINES   OF   ANDROSCOGGIN    GLACIER. 

The  basal  character  of  the  drift  is  also  seen  at  the  terminal  moraine  of 
the  local  Andi-oscoggin  glacier.  This  glacier  formed  terminal  moraines 
near  the  line  between  New  Hampshire  and  Maine.  PI.  XXV,  B,  shows 
the  moraine  on  the  north  side  of  the  river  rising  on  the  slopes  of  Hark  Hill. 
If  it  carried  surface  moraines,  the  glacier  ought  to  have  deposited  contem- 
poraneously with  this  moraine  a  lateral  moraine  comparable  with  it  in  size. 


=!S*^iS^—  ^ 


'i'i        .    r 


1       TERMINAL   MORAINE     ON    ROAJ    FROM    WALDOBORO   TO    NORTH    WALDOBORO       LOOKINls    tAbT 
Ice  f  ow  wai  f  o-n  the    eft 


l;      TERMINAL    MORAINE   OF    LOCAL   ANDROSCOGGIN    GLACIER;   GILEAD. 


BNGLACIAL  DEBRIS.  275 

At  various  2)oints  on  the  hills  that  border  the  valley  I  found  heaps  of  till 
of  various  shapes,  but  they  have  the  forms  of  accumulations  of  englacial 
till.  The  only  deposit  having  distinctly  the  form  of  a  lateral  moraine  that 
I  found  in  the  valley  is  situated  on  the  north  side  of  the  river  and  about  a 
mile  east  of  the  Lead  Mine  bridge  in  Shelburne.  This  is  one-third  of  a 
mile  or  less  in  length,  and  its  origin  is  somewhat  uncertain.  The  hills  on 
each  side  rise  often  steepl)'  to  a  height  of  500  to  2,500  feet,  and  surface 
moraines  were  as  likely  to  form  in  this  valley  as  in  any  in  New  England 
except  a  few  in  the  heart  of  the  White  Mountains. 

At  all  the  other  terminal  moraines  found  in  Maine  the  absence  of 
lateral  moraines  emphasizes  the  conclusion  that  there  was  but  little  morainal 
matter  borne  on  the  surface  of  the  ice  that  was  derived,  like  the  moraines 
of  glaciers  of  the  Alpine  type,  from  avalanches  and  debris  sliding  from 
above  onto  the  ice. 

Agassiz  long  ago  reached  the  conclusion  that  the  ice-sheet  covered  all 
the  land,  and  hence  the  only  way  for  morainal  debris  to  get  into  the  ice 
was  from  below.  The  above-stated  facts  prove  that  late  in  the  ice  epoch, 
after  the  time  when  the  higher  hills  began  to  rise  above  the  ice,  not  much 
debris  fell  from  above  onto  the  ice,  even  in  valleys  bordered  by  steep  hills. 
Up  to  the  very  last  the  drift  was  almost  wholly  basal. 

QUANTITY    OF   ENGLACIAL    DEBRIS. 

The  depth  of  the  upper  or  englacial  till  does  not  necessarily  give  an 
estimate  of  the  quantity  of  morainal  matter  contained  in  the  ice  at  one 
time.  If  we  conceive  the  ice-sheet  suddenly  divested  of  all  motion,  the 
scattered  mass  or  sheet  of  englacial  till  left  when  the  ice  melted  will  repre- 
sent the  amount  of  debris  in  the  ice  at  that  time.  But  if  the  ice  is  in 
motion  the  case  will  be  far  different.  Whenever  the  forward  flow  of  the 
ice  equals  the  terminal  melting  the  iee  front  is  stationai-y  and  a  terminal 
moraine  gathers  as  a  frontal  ridge.  As  the  ice  advances,  the  debris  con- 
tained in  a  zone  of  ice  perhaps  a  half  mile  or  more  in  breadth  is  brought 
forward  and  dropped  on  the  narrow  moraine.  In  other  words,  the  thickness 
of  the  moraine  may  represent  the  englacial  matter  not  only  of  an  area  of 
ice  equal  to  that  of  the  moraine  but  many  times  this  area.  If  now  the 
melting  comes  to  exceed  the  rate  of  advance,  a  series  of  parallel  moraines 


276  GLACIAL  GEAVELS  OP  MAINE. 

will  be  formed,  and  if  the  rate  of  recession  is  uniform,  these  successive 
moraines  become  confluent,  as  a  sheet. 

This  I  conceive  to  be  the  best  interpretation  of  the  upper  or  englacial 
till.  Only  where  the  ice  was  stagnant  does  it  represent  the  quantity  of 
debris  in  the  ice  at  the  final  melting,  and  only  locally  was  it  stagnant. 
Where  the  ice  was  in  motion  the  thickness  of  eng-lacial  till  may  several  or 
many  times  exceed  the  quantity  of  englacial  matter,  comparing  equal  areas 
of  ice  and  land. 

There  are  numerous  places  where  the  rock  is  bare  of  till  or  the  till  is 
very  thin.  We  here  have  proof  that  there  were  considerable  areas  of  tlie 
ice  that  contained  no  glacial  debris  at  the  time  of  final  melting.  The  inter- 
pretation of  this  fact  is  a  matter  of  doubt.  Many  of  the  places  bare  of  till 
are  on  the  tops  of  hills  that  have  deep  sheets  of  subglacial  till  on  their 
northern  slopes.  The  situation  suggests  that  possibly  the  ice  had  been 
robbed  of  its  englacial  material  Avhile  passing  up  the  northern  slopes  of  the 
hills.  We  may  here  have  a  glimpse  of  a  general  scantiness  of  englacial 
matter  when  the  ice  had  become  thin  and  ready  to  disappear,  or  we  may 
assume  only  local  deficiency. 

The  terminal  moraines  are  from  10  up  to  100  feet  high.  How  many 
years'  accumulation  they  represent  is  now  unknown.  The  least  possible 
time  we  could  allow  is  a  single  season,  and  an  advance  of  the  icezzO.  This 
would  give  as  the  utmost  admissible  thickness  of  englacial  matter  5  to  50 
feet.  But  if  the  ice  was  stationary,  during  the  subsequent  recession  a  sheet 
of  the  same  thickness  or  thereabout  ought  to  have  been  formed,  and  it  was 
not  so  formed.  This  proves  that  the  hypothesis  of  stationary  ice  is  inad- 
missible. Structurally  the  moraines,  at  least  those  of  Maine,  can  not  be 
explained  unless  the  ice  was  in  motion.  The  retreatal  moraines  of  the 
Muir  glacier  may  possibly  be  a  type  of  some  of  the  moraines  of  the  Andros- 
coggin glacier,  but  not  of  any  others.  The  proof  is  irresistible  that  the 
moraines  represent  the  debris  of  an  area  of  ice  much  broader  than  their 
bases.  The  sheet  of  englacial  till  that  covers  most  of  the  land  is  a  more 
doubtful  subject  of  interpretation.  In  a  given  place  it  may  or  may  not 
represent  terminal  accumulations. 

Without  venturing  on  very  definite  figures,  and  allowing-  for  great  local 
inequalities,  I  assume  that  the  ice  in  Maine  at  a  given  place  contained  simul- 
taneously only  a  few  feet  of  morainal  matter,  perhaps  a  maximum  of  20 


GROUND  MORAINE.  277 

feet,  and  over  most  of  the  State  very  much  less;  in  the  shite  regions  often 
only  a  foot  or  two  and  from  that  down  to  0. 

GROUND    MORAINE. 

Excavations  at  the  bases  of  the  terminal  moraines  ought  to  exhibit  well 
the  diflPerences  between  the  englacial  and  the  subglncial  till.  The  moment 
we  assume  that  the  moraines  were  of  englacial  origin  we  are  logically 
driven  to  look  for  a  different  origin  for  the  lower  layers  of  the  till.  For 
the  matter  of  the  moraines  (englacial  matter)  shows  little  glaciation,  while 
that  of  the  lower  part  of  the  till  is  intensely  glaciated.  It  is  just  what . 
should  be  expected  if  it  is  a  moraine  profonde.  Accumulations  of  it  have 
a  curved,  flowing  outline,  quite  unlike  the  heaps  into  which  the  englacial 
till  was  often  thrown.  These  are  the  two  fundamental  arguments  for  the 
existence  of  a  ground  moraine.  Expanded  they  are  as  follows:  A  moraine 
profonde  consists  of  dtibris  that  has  been  between  moving  ice  and  the 
underlying  rock.  A  rock  fragment  can  not  be  in  such  a  situation  without 
being  subjected  to  great  attrition  against  the  rock  or  against  other  frag- 
ments if  the  ice  preserves  the  known  rigidity  of  ice  under  ordinary  condi- 
tions It  has  often  been  assumed  that  under  extremely  great  pressure  ice 
becomes  much  more  fluent  or  plastic  than  at  ordinary  pressures.  If  this  be 
so,  what  bearing  has  the  fact  on  the  nature  of  the  glaciation? 

Whatever  theory  of  the  origin  of  the  lower  or  intensely  glaciated  till 
we  adopt  we  must  make  it  consistent  with  two  facts:  First,  all  the  known 
excavations  that  penetrate  to  the  bottom  of  the  till  reveal  glaciated  rock. 
Either,  then,  the  whole  mass  of  the  lower  till  was  rolled  or  dragged  bodily 
beneath  the  ice,  or  each  place  overrun  by  the  ice  was  first  an  area  of  erosion 
and  subsequently  one  of  deposition.  Second,  the  depth  of  the  rock  scor- 
ings, their  straightness  and  length,  require  a  vast  force  to  produce  them. 
The  immense  amount  of  ddbris  that  has  been  fractured  or  ground  to  rock 
flour  or  scratched  and  polished  is  the  ample  counterpart  of  the  very  great 
abrasion  of  the  rock.  No  theories  of  the  superior  fluidity  of  ice  under 
enormous  pressures  or  under  any  other  conditions  can  be  allowed  to  obscure 
the  fact  that  at  the  time  the  rocks  were  scored  the  stones  that  did  the  work 
were  moving  under  great  pressures  and  with  wonderful  steadiness  of  move- 
ment. The  increase  in  plasticity,  if  such  there  was,  was  not  sufficient  to 
impair  seriously  the  rigidity  of  the  ice.     If  the  stones  that  were  ground 


278  '    GLACIAL  GEAVELS  OF  MAINE. 

against  the  solid  rock  were  held  embedded  in  the  ice,  it  was  solid  enough 
to  deserve  the  name  of  ice.  If  they  were  rolled  or  dragged  beneath  it, 
only  solid  ice  could  furnish  the  necessary  friction.  No  matter  what  theories 
we  indulge  as  to  basal  melting  or  semifluidity  under  sufficient  pressure,  or 
as  to  the  conditions  prevailing  at  any  given  point  when  it  was  a  place  of 
deposition  of  stationary  ground  moi-aine,  we  must  admit  that  over  the  area 
of  erosion  at  any  period  in  the  history  of  the  ice-sheet  there  was  a  body  of  ice 
beneath  which,  under  the  enormous  pressure  extended,  terranes  were 
turned  to  dust.  The  marks  of  this  tremendous  conflict  are  conspicuously 
shown  by  the  lower  till  and  not  by  the  upper.  Plainly  they  are  what 
should  be  expected  of  material  that  has  been  beneath  the  ice. 

Again,  the  deeper  aecunmlations,  such  as  the  drumlins  and  the  sublen- 
ticular sheets  on  the  hillsides,  have  a  rounded  outline.  Under  the  action  of 
water  waves  a  sand  or  gravel  bar  assumes  the  form  most  favorable  to  its 
stability,  and  a  mass  of  debris  ought  to  assume  a  corresponding  form  while 
ice  flowed  over  it.  The  drumlins  often  show  beautiful  curves  and  billows, 
and  the  type  of  ground-moraine  scenery  is  very  different  from  that  of 
moraines  either  of  surface  or  englacial  debris.  The  latter  show  more  variety 
of  form  and  gradient  of  slope  and  have  a  more  or  less  heaped  appearance. 

It  is  perhaps  now  impossible  for  us  to  form  an  accurate  picture  of  the 
relations  of  the  englacial  and  subglacial  morainal  matter  to  each  other  and 
to  the  subjacent  rock.  We  know  that  the  englacial  till  is  but  little  glaciated, 
and  hence  must  have  entered  the  ice  before  being  rolled  or  dragged  between 
the  ice  and  the  rock.  We  do  not  know  in  detail  the  manner  of  its  entrance 
into  the  ice,  though  that  must  have  occurred  soon  after  the  flow  was 
established,  or  possibly  even  before  the  flow  of  consolidated  ice  began. 
We  do  not  know  the  relation  of  this  assumption  of  englacial  matter  to  the 
history  of  the  adjacent  regions.  We  do  not  know  certainly  whether  the 
stones  and  particles  of  the  ground  moraine  were  from  the  first  and  con- 
stantly beneath  the  ice,  or  whether  each  particle  was  at  one  time  within  the 
ice  and  was  subsequently  torn  from  its  grasp,  or  whether  both  kinds  of 
matter  are  now  a  part  of  the  subglacial  till,  though  there  is  a  strong  proba- 
bility that  the  last-stated  hypothesis  is  the  true  one.  How  much  of  the 
ground  moraine  was  stationary  during  the  time  of  the  accumulation!  We 
do  not  know  the  height  in  the  ice  attained  by  the  englacial  debris,  nor  its 
vertical  and  horizontal  distribution.     In  a  general  way  we  know  that  it  got 


GEOUND  MORAINE.  279 

into  the  ice  before  it  had  been  much  overridden  and  glaciated;  that  the 
region  of  chief  deposition  of  the  subglacial  till  was  near  the  front  of  the 
ice-sheet,  where  the  ice  was  thinner;  that  back  of  this  region  there  was 
another  zone,  perhaps  found  not  very  far  below  the  distal  margin  of  the 
n^v(^,  where  pressure  and  velocity  of  motion  united  to  produce  great  ero- 
sion of  the  rock  and  transportation  of  subglacial  ddbris,  while  under  the 
nev^  transportation  was  less  active,  whether  because  of  the  depth,  or  the 
structural  condition  of  the  snow  and  ice,  or  other  causes,  is  unknown.  But 
while  the  details  are  thus  uncertain,  the  fact  of  the  existence  of  the  g'round 
moraine  is  satisfactorily  established. 

In  the  foregoing  discussion  it  has  been  assumed  that  the  ground  moraine 
was  wholl}^  formed  between  the  ice  and  the  rock,  and  that  the  flowing  out- 
lines of  accumulations  were  carved  by  the  ice  flowing  over  them.  There 
is  a  possible  alternative  theory  that  perhaps  ought  to  be  noticed.  No  mat- 
ter whether  we  consider  the  flow  of  the  ice  as  plastic  or  viscous,  we  can 
conceive  of  a  mass  whose  internal  friction  is  so  great — forming,  as  it  were,  a 
mass  of  till  infiltrated  with  films  and  threads  of  ice — that  it  could  remain 
embayed  while  the  purer  ice  flowed  over  or  ai'ound  it.  Such  an  embayed 
mass  (half-till,  half-ice)  would  be  carved  into  the  lenticular  form  as  the 
glacier  flowed  over  it,  just  as  if  it  were  a  mass  of  true  subglacial  moraine. ' 

In  reply  to  this  it  may  be  said  that  if  debris  scattered  through  the 
lower  part  of  the  ice  were  reached  by  heat  rays  from  the  sun  or  other 
source  of  heat  external  to  itself  it  would  absorb  the  heat  and,  by  melting 
the  ice  in  contact  with  it,  might  increase  the  fluency  (or  plasticity)  even 
more  than  the  friction  of  the  stones  diminished  it.  Certain  bowlders  in  the 
Alps  have  been  supposed  to  rise  upward  in  the  ice  in  consequence  of  the 
absorption  of  solar  heat  by  their  upper  surfaces.^  The  instances  where  thin 
glaciers  have  been  observed  to  flow  over  bowlders  without  pushing  them 

'It  has  been  contended  that  rocks  warmed  from  above  naturally  rise  in  the  ice.  This  is  doubt- 
ful as  a  general  proposition.  The  ice  melts  with  contraction  of  volume,  leaving  a  small  cavity  above 
the  water.  Molecular  heat  could  then  no  longer  produce  melting  except  where  the  ice  was  in  contact 
with  the  water.  The  upward  melting  could  proceed  from  radiant  heat  alone,  while  the  radiant  molec- 
ular heat  communicated  to  the  water  would  be  largely  transferred  to  the  bottom  of  the  cavity,  the 
water  of  39^  seeking  the  bottom.  Whether  as  a  net  result  the  melting  would  be  most  rapid  upward 
or  downward  would  depend  on  the  size  of  the  fragments,  their  shape,  etc.  If  it  be  contended  that 
the  ice  from  beneath  would  push  the  stone  upward  fast  enough  to  fill  the  cavity  of  melting,  we  must 
demand  the  proof  of  such  action  against  the  force  of  gravity.  This  note  applies  only  to  the  supposed 
rising  of  debris  in  the  ice  owing  to  heat  from  above.  Whether  vertical  ice  movements  could  raise  the 
debris  is  a  very  different  question. 


280  .  GLACIAL  GRAVELS  OF  MAINE. 

forward  (Niles^  and  Spencer'),  also  over  sand  and  gravel  without  disturb- 
ing the  stratification  (Chamberlin^),  may  be  due  in  part  to  radiant  heat 
absorbed  by  the  bowlders  or  communicated  directh^  to  the  ice.  It  is  uncer- 
tain to  what  depth  solar  heat  penetrates  the  ice,  yet  during  the  decay  of 
the  ice-sheet  a  time  must  have  come  when  the  sun  could  penetrate  the  thin 
ice  to  the  moraine  stuff  scattered  through  it. 

In  attempting  to  sum  up  this  controversy  I  find  too  much  hypothesis 
and  too  little  fact.  It  is  important  to  study  in  the  field,  if  possible,  the 
effect  of  a  large  amount  of  englacial  matter  on  the  rate  of  flow.  In  the 
present  state  of  the  case  it  must  be  considered  doubtful  if  any  large  accu- 
mulations of  till  have  been  made  in  this  way.  If  there  were  such  masses 
of  ice  embayed  because  of  the  contained  till,  the  till  would  be  upper  i-ather 
than  lower  till,  or  at  least  a  transition  between  them.  The  matter  of  the 
lenticular  hills  has  been  thoroughly  glaciated,  and  it  remains  to  be  proved 
that  the  mutual  friction  of  till  fragments  in  a  mass  of  partially  stagnant 
ice  could  simulate  the  greater  attrition  which  must  inevitably  mark  those 
whiph  have  been  ground  against  the  solid  rock  or  against  each  other  at  the 
bottom  of  the  ice. 

Some  other  qiiestions  demand  attention. 

DRUMLINS. 

1.  Were  the  drumlins  accumulated  at  the  ice  front  during  the  retreat 
of  the  ice  at  unequal  rates,  so  that  they  are  a  form  of  terminal  moraine? 
It  can  be  confidently  answered  that  their  shapes  and  materials  are  wholly 
unlike  those  of  the  terminal  moraines  of  Maine. 

2.  During  the  final  melting  of  the  ice  the  surface  would  melt  un- 
equally, since  the  larger  bowlders  and  deeper  masses  of  till  would  par- 
tially protect  the  ice  beneath  them  from  melting.  There  would  be  much 
lateral  sliding  of  till  into  the  depressions  thus  formed  on  the  surface,  as 
seen  by  Prof.  Gr.  F.  Wright  on  the  Mtiir  glacier  of  Alaska,  and  this  process 
would  originate  trains   of  bowlders,   and  ridges   and  mounds   of  vai'ious 

'  Upon  the  relative  agency  of  glaciers  and  subglacial  streams  in  the  erosion  of  valleys,  Am.  Jour. 
Soi.,  3d  series,  vol.  16,  pp.  366-370, 1878. 

^ Notes  on  the  erosive  power  of  glaciers  as  seen  in  Norway,  Geol.  Mag.,  new  ser.,  Dec.  Ill;  vol. 
4,  pp.  167-173, 1887. 

^Observations  ou  the  recent  glacial  drift  of  the  Alps,  Trans.  Wisconsin  Acad.  Sci.,  Arts,  and 
Letters,  vol.  5,  pp.  258-270, 1877-81. 


DRUMLINS.  281 

shapes,  and  they  would  be  composed  of  upper  till,  not  the  intensely  gla- 
ciated lower  till,  unless  first  eroded  and  then  i-ebuilt  by  the  glacier.  It  is 
difficult  to  conceive  how  smoothly  rounded  hills  in  such  large  numbers  and 
of  such  great  size  could  result  from  this  process.  Moreover,  some  of  the 
masses  of  thoroughly  glaciated  matter  are  long  ridges  parallel  with  the 
glaciation.  These  are  still  more  difficult  of  explanation  as  being  due  to 
accumulations  in  surface  hollows  of  the  ice.  Osars  or  sandy  ridges  would 
result,  not  masses  of  till  containing  much  rock  flour. 

3.  Are  the  deep  masses  of  till  remains  of  a  former  sheet  of  till  of 
which  the  greater  part  has  been  eroded  hj  the  sea  waves,  as  suggested  by 
Prof  N.  S.  Shaler'F  This  can  not  have  been  the  case  in  Maine,  for  the 
following  reasons: 

First.  These  deep  masses  of  till  are  sometimes  1  mile  or  more  from 
any  other  similar  mass.     The  amount  of  erosion  required  is  enormous. 

Second.  The  presence  of  continuous  beaches  from  high  level  down  to 
the  sea,  shown  on  Monhegan  Island  and  other  exposed  coasts,  proves  that 
if  great  masses  of  till  had  been  eroded  most  of  the  larger  stones  would 
now  remain  as  broad  sheets  in  the  valleys  or  as  terraces  on  the  hillsides. 
On  the  other  hand,  the  beach  gravels  of  Maine  are  relatively  scanty  and 
bear  no  relation  to  the  positions  of  the  drumlins. 

Third.  The  coast  region,  where  the  lenticular  hills  are  most  immerous, 
is  largely  covered  by  marine  sands  and  clays.  If  the  till  was  eroded  in  the 
manner  supposed,  the  erosion  must  have  occurred  before  the  deposition  of 
these  marine  beds.  These  beds  would  preserve  the  beach  gravels  beneath 
them  from  erosion.     No  such  rolled  gravels  now  exist  beneath  the  clays. 

Fourth.  If  we  suppose  that  there  has  been  such  an  erosion  of  the  till, 
we  must  account  for  the  fact  that  the  kames  and  marine  deltas  deposited  in 
the  sea  by  the  glacial  rivers  have  escaped  in  such  good  state  of  preservation. 

Fifth.  The  lenticular  sheets  of  till  on  the  northern  slopes  of  hills  must 
have  substantially  the  same  orighi  as  the  drumlins  themselves.  They  lie 
inclined  against  the  hills  and  reach  upward  on  the  slopes  for  several 
hundred  feet.  The  erosion  required  to  carve  away  the  suiTounding  por- 
tions of  a  former  deep  sheet  of  till  to  such  great  heights  must  certainly  have 
left  its  mark.     Yet  there  are  multitudes  of  these  hillside  lenses  in  reg-ions 


■Illustrations  of  the  earth's  surface:  Glaciers,  by  Shaler  and  Davis,  p.  63,  Boston,  James  R. 
Osgood  &  Co.,  1881,  4-^. 


282  GLACIAL  GEAVBLS  OF  MAINE. 

where  all  the  vigilance  of  road  overseers  and  selectmen  exercised  for  years 
has  not  succeeded  in  finding  a  wagon  load  of  genuine  water-washed  gravel. 
4.  Are  the  drumlins  remains  of  a  former  sheet  of  till  irregularly  eroded 
by  the  glacier!  I  do  not  know  how  a  glacier  can  deposit  till  and  not  at 
the  same  time  also  deposit  glacial  gravel.  Glacial  sti-eams  are  inseparable 
from  a  glacier.  The  work  of  the  latest  ice-sheet  is  a  fair  sample  of  what 
former  ice-sheets  did,  differing  only  as  they  have  differed  in  size  or  time  of 
continuance.  Now  the  latest  Ice  period  has  left  hundreds  of  sqiiare  miles 
covered  with  well-rounded  stones  and  bowlders  distributed  over  a  large 
part  of  this  State,  as  well  as  of  New  England  generally.  If  at  any  future 
time  Maine  is  again  glaciated,  those  rounded  stones  will  be  incorporated  in 
the  till  or  pushed  bodily  out  into  the  Gulf  of  Maine,  bding  more  or  less 
changed  in  shape  during  the  process,  but  still  being  quite  different  in  form 
from  angular  stones  of  fracture.  It  is  possible  to  conceive  of  glaciation  so 
severe  as  to  remove  all  the  glacial  gravels  from  Maine  into  the  sea,  but 
farther  west,  where  the  outer  terminal  moraines  are  deposited  on  the  land, 
the  water-rounded  stones  of  the  last  ice-sheet  would  appear  in  the  moraines. 
If  any  one  claims  that  the  lenticular  hills  are  remains  of  the  till  of  a  former 
Ice  period  that  failed  to  be  eroded  by  the  latest  invasion  of  the  ice,  on 
him  rests  the  burden  of  proving-  that  the  till  and  terminal  moraines  of 
southern  New  England  contain  a  sufficient  number  of  once  rounded  stones 
and  bowlders  to  account  for  the  glacial  gravels  of  such  supposed  more 
ancient  ice-sheet  and  which  the  later  ice  incorporated  into  its  own  deposits. 
Of  course  it  is  assumed  that  if  a  sheet  of  till  can  be  eroded  by  ice,  masses 
of  sediments  would  sooner  be  eroded.  For  the  present  the  theory  under 
examination  can  not  be  insisted  on. 

RELATION   TO   MARINE   GRAVELS. 

The  relation  of  the  lower  till  to  the  beach  gravel  deserves  notice  in 
this  connection. 

A  good  place  for  study  of  the  subject  is  at  Matinicus  Island.  A 
lenticular  mass  of  till  10  to  50  feet  deep  covers  the  western  portion  of  the 
island,  as  is  proved  by  the  cliff  of  erosion  at  the  present  beach  and  by 
wells.  The  till  is  everywhere  covered  by  a  few  feet  of  beach  gravel.  The 
till  is  very  fine  in  composition,  is  very  compact  and  intensely  glaciated,  has 
a  dark-blue  color,  and  is  typical  lower  till,  very  different  from  the  matter  of 


EELATION  OF  LOWER  TILL  TO  MARINE  GRAVELS.  283 

the  Waldoboro  moraine.  At  the  time  the  sea  stood  at  its  highest  level  the 
water  would  be  about  150  feet  deep  over  the  top  of  the  island.  Here  then 
is  a  good  place  to  observe  the  effect  of  the  sea  waves  on  the  ice  and  its 
contained  till  as  the  ice  front  retreated  northward.  If  this  lenticular  mass 
of  till  was  contained  in  an  embayed  mass  of  ice  rendei'ed  viscous  by  the 
amount  of  solid  matter  distributed  through  it,  or  if  it  was  cast  out  at  the 
ice  front  as  any  kind  of  frontal  moraine,  then  we  ought  to  find  the  till  more 
or  less  assorted  by  water  unless  the  ice  had  melted  with  extraordinary 
quietness  before  the  elevation  of  the  sea.  A  multitude  of  facts  furnished 
both  by  the  terminal  moraines  and  by  the  deltas  deposited  by  g-lacial  rivers 
in  the  sea,  as  well  as  b}^  the  valley  drift  of  the  river  valleys,  point  to  the 
conclusion  that  the  sea  stood  at  high  level  during  all  the  later  part  of 
glacial  time.  On  Munjoy  Hill,  Portland,  are  a  number  of  small  irregular 
masses  of  sand,  filling-  pockets  in  the  clayey  till.  They  are  found  only  near 
the  surface.  In  the  lower  part  of  the  deep  masses  of  till  I  have  found  no 
water-classified  matter.  The  presence  of  signs  of  water,  either  glacial 
streams  or  marine  waves,  in  the  upper  portion  of  the  till  only  makes'their 
absence  in  the  lower  till  still  more  suggestive. 

The  relations  of  the  beach  gravels  to  the  deep  masses  of  till  are  not 
only  perfectly  consistent  with  the  subglacial  origin  of  the  lower  till,  but 
distinctly  favor  this  hypothesis. 

On  the  whole,  we  may  affirm  that  whether  we  regard  the  composition 
of  the  lowest  portion  of  till,  or  its  relations  to  the  terminal  moraines  or  to 
the  glacial  gravels  on  the  marine  deposits,  all  find  their  simplest  explanation 
in  the  hypothesis  of  a  ground  moraine. 

It  is  not  asserted  that  a  ground  moraine  covered  all  of  Maine.  It  is 
well  known  that  many  places  are  bare  of  till  where  there  has  been  no 
erosion  by  the  sea  or  streams.  There  are  places  where  probably  only  sub- 
glacial  till  is  present,  and  others  where  the  till  was  all  englacial,  or  nearly 
so.  Neither  is  the  line  of  demarcation  between  these  two  deposits  always 
sharply  defined.  Indeed,  they  graduate  one  into  the  other  so  as  often  to 
i-ender  it  difficult  to  make  out  the  line  of  separation.  Probably  the  lower 
the  point  in  the  ice  where  morainal  fragments  occurred,  the  more  glaciated 
they  would  be — a  sufficient  cause  of  gi-adations  in  glaciation  between  the 
upper  and  the  lower  till. 


284  GLACIAL  GKAVELS  OF  MAINE. 

BOWLDER    FIELDS    AND    TRAINS. 

Many  details  as  to  the  till  are  here  omitted,  as  not  bearing  on  the  sub- 
ject of  the  g'lacial  gravels.  One  phenomenon  must,  however,  be  noted — 
the  bowlder  fields.  In  a  certain  sense  the  whole  of  the  granitic  regions 
might  be  considered  as  bowlder  fields.  But  the  fields  referred  to  are  dif- 
ferent. They  lie  in  regions  of  coarse  slates.  The  whole  surface  is  so  cov- 
ered by  slabs,  up  to  6  or  8  feet  long,  that  one  can  travel  a  half  mile  by 
stepping  from  bowlder  to  bowlder.  The  only  soil  is  found  2  to  5  feet  below 
the  surface.  The  babbling  of  invisible  streams  is  heard  as  they  make  their 
way  among  the  bowlders.  Raspberry  bushes  peer  up  through  the  rifts 
between  them.  One  of  these  bowlder  fields  is  found  about  a  mile  south  of 
Tomah  station  of  the  Maine  Central  Railroad.  This  is  situated  near  the 
junction  of  two  large  glacial  rivers,  and  the  finer  parts  of  the  till  may  have 
been  washed  away  by  the  waters.  I  observed  a  still  larger  bowlder  field 
in  T.  7,  R.  4,  Aroostook  County.  It  is  situated  2  miles  from  any  known 
osar,  and  its  cause  is  obscure. 

In  the  wilderness  between  Aurora  and  Deblois  a  train  of  huge  granite 
bowlders,  which  is  parallel  with  the  glacial  scratches  of  the  region,  is  inter- 
sected obliquely  by  the  Katahdin  osar.  The  bowlders  are  piled  one  above 
another  so  as  to  form  a  ridge,  and  some  of  them  overlie  the  gravel.  The 
bowlder  trains  bear  a  relation  to  outcrops  of  granite  rocks,  but  are  not  lateral 
to  valleys.  The  appearances  indicate  that  they  were  not  medial  or  lateral 
surface  moraines,  but  either  distinctly  subglacial  or  stranded  basal  matter, 
so  that  in  their  ridge-like  development  they  are  drumlins  of  coarser  material 
than  the  ordinar}'. 

WAS  THERE  MORE  THAN  ONE  GLACIATION  OF  MAINE? 

The  observations  of  White,  Winchell,  Upham,  Chamberlin,  Salisbury, 
McGee,  and  others  in  the  Upper  Mississippi  Valley  prove  that  there  were  at 
least  two  principal  advances  of  the  ice,  separated  by  a  rather  long  interval. 
It  has  since  been  a  special  object  of  search  to  Eastern  geologists  to  find 
similar  advances  in  the  Northeast.  At  one  time  it  appeared  probable  that 
I  had  found  traces  of  two  tills  that  might  belong  to  different  periods.  The 
dam  of  the  Penobscot  River  where  it  flows  out  of  South  Twin  Lake  had 
broken  a  short  time  before  my  A'isit  to  the  place.     The  water  had  escaped 


WAS  THEEE  A2^  INTERGLACIAL  PERIOD  IN  MAINE  ?  285 

around  the  end  of  the  woodeu  part  of  the  dam  and  eroded  a  channel  in  the 
earth,  thus  atfording  a  fresh  section  down  to  the  soHd  rock.  At  the  bottom 
were  several  feet  of  a  hard,  tough,  clayey  till  that  resisted  erosion  wonder- 
fully and  broke  up  into  blocks  2  to  3  feet  in  diameter. 

Above  this  was  a  lighter-colored  and  less  compact  till  forming  a  north- 
and-south  ridge  or  elongated  ch'umlin.  The  material  was  indistinctly 
arranged  in  layers,  yet  was  not  an  osar  composed  of  water-transported 
matter,  but  was  true  unmodiiied  till.  The  great  contrast  between  the  tough 
under  stratum  and  the  more  siliceous  overlying  layer  made  me  suspect  that 
here  were  the  ground  moraines  of  two  different  ice-sheets.  Subsequent 
observations  in  man}'  parts  of  the  State  have  convinced  me  that  this  phe- 
nomenon, which  is  a  very  common  one,  is  probably  due  to  the  overlap  of 
till  derived  from  two  different  kinds  of  rock.  Thus  at  South  Twin  Lake 
the  local  rocks  are  slates  and  other  fine-grained  schists.  The  lowest  (bine) 
stratum  of  the  till  is  dei'ived  from  the  local  rocks,  while  the  overlying  ridge 
(also  a  part  of  the  ground  moraine)  is  composed  of  matter  transported  from 
the  granitic  region  about  Mount  Katahdin,  situated  not  far  to  the  north. 
This  overlapping  of  till  having  different  characters  is  found  wherever  the 
ice  passed  from  one  kind  of  rock  into  an  area  of  another  kind.  We  do 
not  need  to  postulate  two  glacial  periods  in  order  to  account  for  it,  although 
that  is  certainly  possible.  It  is  just  what  should  be  expected  in  the  case  of 
an  ice-sheet  moving  over  areas  of  different  kinds  of  rock,  pro^dded  the 
ground  moraine  was  not  all  formed  simultaneously,  but  each  region  was  first 
an  area  of  denudation  and  subsequently  of  accumulation.  During  the 
first  period  of  denudation  the  scratching  was  produced.  The  first  of  the 
embayed  ground  moraine  would  be  composed  chiefl}'  of  local  matter,  which 
would  subsequently  be  overlain  with  far-traveled  matter. 

All  parts  of  the  State  have  been  examined  without  finding'  peats  or  soils 
within  the  till,  or  anything  indicating  an  interglacial  period  in  Maine. 

The  relation  of  the  marine  clays  to  the  till  deserves  special  study.  I 
could  find  no  fresh  exposures  showing  the  relations  of  the  Waldoboro 
moraine  to  the  marine  clay.  On  the  surface  the  clay  overlay  the  moraine, 
but  the  base  was  not  seen.  At  Sabatis  Village  the  marine  clays  also  over- 
lay the  terminal  moraine,  to  a  depth  of  8  feet,  but  the  base  of  the  moraine 
was  not  exposed.  It  is  thus  imcertain  whether  at  the  base  the  terminal 
iporaines  cover  the  marine  clays  or  not. 


286  GLACIAL  GRAVELS  OF  MAINE. 

Since  1861  Prof.  C.  H.  Hitchcock  has  repeatedly  expressed  the  behef 
that  two  advances  of  the  ice  are  provea  by  the  relations  of  the  upper  till 
to  the  fossiliferous  marine  clays  at  Portland.^  The  same  opinion  has  been 
expressed  in  the  geological  reports  of  New  Hampshire.  Professor  Hitch- 
cock's latest  conclusions  are  contained  in  his  report  as  a  member  of  the 
American  Committee  of  the  International  Congress  of  Geologists:^ 

*  *  *  Very  clear  evidence  of  the  relations  of  the  fossiliferous  beds  to  both  tills 
is  found  at  Portland,  Maine.  Here  clays  and  sands  rise  about  100  feet  above  the  sea 
and  hold  121  species  of  organisms,  all  of  living  forms.  They  rest  upon  typical  lower 
till,  and  are  overlain  by  as  much  as  50  feet  thickness  of  upper  till.  At  the  time  the 
reporter  described  these  facts  the  prevalent  doctrine  of  the  triple  nature  ot  the  glacial 
period  had  not  been  established;  b.ut  it  seems  clear  that  two  seasons  of  ice  presence 
are  indicated  at  this  locality.  *  *  * 

The  meaning  of  the  terms  "interglacial,"  as  well  as  "upper"  and 
"lower"  till,  must  be  made  definite  when  used  in  this  connection.  The  use 
of  the  term  interglacial  as  of  world-wide  application  can  not  be  warranted 
until  the  facts  are  all  in;  for  the  present  it  can  only  be  admitted  to  express 
the  facts  in  particular  regions  explored,  e.  g.,  the  Mississippi  Valley,  large 
parts  of  Europe,  etc.  At  the  great  terminal  moraines  there  may  have  been 
many  advances  and  retreats  of  the  ice,  and  one  studying  the  till  there 
might  come  to  the  conclusion  that  there  had  been  many  glacial  and  inter- 
glacial periods,  and  so  there  would  have  been  at  his  place  of  study  and 
from  his  standpoint;  yet  all  these  advances  of  the  ice  might  be  comprised 
within  what  another  would  consider  as  a  single  invasion  of  the  ice,  mere 
minor  accidents  of  a  larger  movement.  So,  too,  the  term  "upper"  till  may 
mean  englacial  till,  or,  where  there  are  tills  deposited  during  two  distinct 
advances  of  the  ice  separated  by  a  warmer  climate,  it  may  mean  the  later 
of  these  tills  The  use  of  the  term  by  Professor  Hitchcock  in  connection 
with  the  reference  to  the  triple  nature  of  the  Grlacial  period  seems  to  indi- 
cate that  he  considers  the  two  seasons  of  ice  presence  at  Portland  as  the 
correlative  of  the  two  glacial  epochs  of  the  interior. 

Let  us  review  the  points  brought  out  by  Professor  Hitchcock: 
1.  The  locality  cited  is  situated  at  the  western  end  of  Portland,  where 
there  have  been  extensive  landslips,  aud  it  is  difficult  to  determine  what  was 
the  original  order  of  deposition.     The  proof  of  so  important  an  event  as  an 

'Thus,  in  the  Prelimiaary  Report  upon  the  Natural  History  and  Geology  of  the  State  of  Maine, 
1861,  p.  275:  "  We  have  recently  noticed  that  in  Portland  these  clays  underlie  a  coarse  deposit,  which 
has  always  been  referred  to  the  uumodilied  drift,"  etc. 

-Am.  Geol.,  vol.  2,  p.  302. 


WAS  THBEE  AN  INTBRGLACIAL  PERIOD  IN  MAINE?  287 

interglacial  period  ought  to  rest  in  observations  made  in  more  places  than 
one,  and  in  places  where  there  can  be  no  suspicion  of  landslips. 

2.  I  have  examined  the  place  since  reading  Professor  Hitchcock's  pub- 
lications, also  after  he  has  kindly  written  me  descriptions.  Near  the  same 
locality  Dr.  William  Wood  and  Mr.  C.  B.  Fuller,  of  the  Portland  Society 
of  Natural  History,  have  recently  exhumed  a  skeleton  of  a  Avalrus  in  sandy 
clays.  I  have  examined  several  excavations  in  that  vicinity  (all  that  are 
now  open),  and  can  not  be  sure  that  I  have  seen  the  exposures  referred  to 
by  Professor  Hitchcock.  I  have  found  masses  of  rounded  cobbles  and 
bowlderets  overlying  the  fossiliferous  marine  beds,  also  small  masses  of 
more  till-like  appearance.  Both  were  in  material  that  had  slipped  down 
from  the  hill  above;  but  not  to  insist  on  this,  let  it  be  assumed  that  both 
kinds  of  deposit  can  there  be  found  overlying  the  marine  beds  in  situ. 

If  the  "upper  till"  referred  to  by  Professor  Hitchcock  is  composed  of 
the  rounded  gravel  and  bowlderets,  we  have  a  case  here  of  transportation 
by  water  as  well  as  by  ice.  The  great  glacial  river  which  reached  from 
the  upper  Androscoggin  Lakes  to  Portland  could  transport  bowlderets 
beyond  the  front  of  the  ice  into  the  sea,  especially  in  the  time  of  summer 
floods.  It  is  a  possible  interpi-etation  that  the  ice  was  confronting  the  sea, 
and  if  so  it  might  often  happen  that  matter  brought  down  by  glacial  rivers 
would  be  dropped  on  marine  beds  previously  laid  down.  The  presence  of 
such  water-rounded  matter  is  not  of  itself  a  proof  of  a  readvance  of  the 
ice  over  the  fossiliferous  clays. 

But  if  this  "upper  till"  was  transported  not  by  water,  but  by  ice,  we 
have  at  Portland  substantially  the  same  problem  as  the  supposed  one  at 
the  Waldoboro  inoraine  overlying  the  marine  clay.  The  problem  is  to 
determine  whether  here  are  two  presences  of  the  ice  such  as  warrant  the 
correlation  of  the  Maine  deposits  with  those  of  the  Interior. 

3.  During  the  latest  glacial  jjeriod  in  the  Northwest  there  were  depos- 
ited the  great  kettle  moraine  and  broad  sheets  of  morainal  drift  (up  to  a 
breadth  of  several  hundred  miles),  vai-ying  in  depth  up  to  400  or  500  feet 
or  more.  The  amount  of  till  overlying  a  supposed  interglacial  clay  at 
Portland,  and  perhaps  at  Waldoboro,  is  inconsiderable  compared  with  the 
great  sheets  and  moraines  of  the  Northwest.  We  can  not  correlate  them 
unless  it  can  be  proved  that  in  Maine  the  ice  carried  les.«  morainal  matter, 
so  that  smaller  moraines  represent  a  greater  relative  time  of  deposition. 


288  GLACIAL  GKAVELS  OP  MAINE. 

4.  The  glaciation  of  the  eountrj  south  of  the  Waldoboro  moraine 
differs  in  no  respect  that  I  can  discover  from  that  of  the  country  north  of 
it,  and  the  same  is  true  of  Portland.  There  'is  no  sig'n  of  the  subaerial 
erosion  that  woukl  result  if  the  ice  only  advanced  to  these  places  after  a 
retreat  at  all  comparable  in  time  to  the  interglacial  epoch  of  the  West,  sup- 
posing the  land  to  have  lieen  above  the  sea.  On  tlie  other  hand,  if  it  was 
beneath  the  sea  during  all  or  even  a  part  of  the  interglacial  period,  we 
ought  to  find  a  different  development  of  the  marine  beds  south  of  those 
places  (the  supposed  line  of  ice  front  during  the  second  advance  of  the  ice) 
from  that  north  of  this  line.  I  do  not  recognize  any  difference  except  the 
general  change  we  discover  everywhere  as  we  go  to  greater  elevations  up 
to  230  feet. 

5.  If  the  supposed  readvance  of  the  ice  at  Portland  over  marine  beds 
is  correlative  to  the  second  glacial  advance  over  the  Northwest,  we  ought 
to  find  everywhere  along  the  coast  a  series  of  terminal  moraines  or  morainal 
sheets  overlying  the  marine  beds.  Only  a  few  places  have  been  found 
where  this  can  be  admitted  as  even  remotely  probable.  The  few  scattered 
bowlders  in  the  marine  clays  can  better  be  accounted  for  as  due  to  ice  floes 
and  small  bergs. 

6.  Existing  glaciers  are  known  to  advance  and  retreat  alternately,  or 
for  a  time  remain  stationary.  Analog}^  requires  us  to  postulate  similar 
behavior  of  the  great  ice-sheet.  It  is  not  necessary  to  correlate  the  time  of 
such  temporary  halts  of  the  extremity  of  the  ice,  or  of  its  readvances,  with 
the  interglacial  period  of  the  Northwest.  They  may  have  been  only  for  a 
few  years  at  most;  not  a  geological  epoch.  The  small  terminal  moraines 
and  supposed  readvances  of  the  ice  in  Maine  correspond  generically  to  the 
smaller  retreatal  moraines  of  southern  New  England  and  the  Northwest. 
At  the  time  of  their  formation  the  doom  of  the  last  ice-sheet  had  Ijeen  pro- 
nounced. The  algebraic  sum  of  the  secular  accumulation  and  waste  of  ice 
had  the  minus  sign,  though  particular  elements  might  be  plus. 

7.  It  is  granted  that  a  thin  body  of  ice  might  advance  over  marine 
sediments  without  eroding  them,  just  as  happened  with  the  soils  of  the 
Upper  Mississippi  Valley.  But  if  the  flow  were  to  continue  long  enough  to 
equal  the  second  advance  of  ice  over  the  Northwest,  a  considerable  body 
of  till,  both  subglacial  and  englacial,  ought  to  be  left  overlying  the  clays. 
The  finding  of  only  small  masses  of  till  or  a  thin  sheet  of  scattered  bowl- 


WAS  THEEE  AN  INTEEGLACIAL  PERIOD  IN  MAINE?  289 

■ders  may  mark  an  advance  of  thin  ice,  but  only  a  temporaiy  one.  If  there 
shall  be  found  in  Maine  unmistakable  subglacial  till  in  situ  overlying  the 
marine  clays,  it  will  indicate  a  much  longer  period  of  advance  than  any 
interpretation  now  allowable. 

8.  If  the  sea  rose  while  the  ice  still  remained,  so  that  the  waves  beat 
u]Don  a  shore  of  ice,  pieces  of  ice  would  from  time  to  time  be  detached, 
partly  as  floating  bergs,  but  in  case  of  ice  containing  euglacial  matter  it 
might  often  happen  that  the  pieces  would  not  float  l^ecause  of  the  morainal 
matter  contained,  and  when  the  ice  melted  such  fragments  would  form  a 
deposit  similar  to  true  glacial-transported  till.  Such  might  often  be  lodged 
in  the  marine  beds  or  glacial  gravels.  I  have  not  sufficient  facts  to  discuss 
the  hypothesis  at  present,  yet  this  question  must  be  considered  before  the 
significance  of  small  till  masses  on  or  in  marine  sediments  can  be  regarded 
as  definitely  determined. 

The  floating  bergs  would  naturally  di'op  fragments  upon  the  sea  bot- 
tom, and  perhaps  sometimes  quite  deep  masses.  These  deposits  must  be 
distinguished  from  matter  brought  to  the  place  of  deposition  by  glacier  ice. 

9.  It  is  agreed  that  the  fossiliferous  sands  and  clays  of  Portland  overlie 
a  fine  blue  clayey  till,  apparently  subglacial.  But  on  the  upper  slopes  of 
the  hills  I  found  fossiliferous  sand  overlying  glacial  gravel.  This  I  regard 
as  beach  sand  and  gravel,  composed  of  the  material  washed  down  from  the 
top  of  the  hill  by  the  waves  of  the  sea.  Glacial  sand  and  gravel  were 
originally  deposited  on  the  tops  of  the  hills.  Part  of  this  deposit  and  per- 
haps some  till  were  subsequently  eroded  by  the  sea  and  strewn  on  the  hill- 
sides. The  alternative  hypothesis  would  be  that  the  fossils  grew  in  the 
sediments  of  the  glacial  streams  as  they  were  poured  out  from  ice  channels 
into  the  sea. 

10.  In  determining  whether  in  a  given  region  there  have  been  two  ice 
periods,  we  have  to  compare  the  shapes  of  the  stones  of  the  till  of  the 
supposed  two  ages.  As  elsewhere  noted,  a  system  of  glacial  streams  is 
inseparable  from  a  glacier,  and  these  waters  leave  a  system  of  glacial  sedi- 
ments. If  ice  subsequently  advanced,  the  rounded  stones  of  this  glacial 
gravel  would  either  be  overridden  by  the  later  glacier  or  be  partly  or 
wholly  eroded  and  pushed  forward  by  it,  and  in  either  case  they  would  be 
found  in  either  the  earlier  or  later  till,  perhaps  at  the  terminal  moraines. 
They  might  be  somewhat  planed  or  modified  in  shape  in  the  process,  yet 

MON   XXXIY- 19 


290  GLACIAL  GRAVELS  OF  MAINE. 

where  there  were  large  numbers  of  them  they  could  hardly  fail  to  betray 
the  fact  that  they  were  once  rounded  by  water  movements  and  were  not 
fragments  of  fracture  and  cleavage.  In  Maine  there  are  places  near  the 
White  ]\Iountains  where  I  found  till  containing  numerous  water-rolled 
stones,  but  in  general  such  matter  is  very  small  in  amount  as  compared 
with  what  was  once  angular  gravel  or  talus  matter.  I  find  in  the  till  no 
adequate  representation  of  the  water-rounded  stones  of  a  more  ancient 
glacier.  In  the  terminal  moraine  near  Waldoboro  there  are  few  it  any 
such;  none  were  observed. 

11.  The  Waldoboro  terminal  moraine  is  6  miles  long,  and  is  much 
larger  than  anything  of  the  kind  at  Portland.  So  far  as  I  have  yet  discov- 
ered, it  does  not  prove  a  readvance  of  the  ice,  but  can  equally  well  be 
assiimed  to  have  been  formed  at  the  ice  front  during  a  pause  in  the  retreat. 
There  is  still  stronger  reason  for  this  conclusion  in  the  case  of  the  Portland 
deposits;  yet  if  it  shall  be  hereafter  proved  that  there  was  an  advance  of 
the  ice  immediately  preceding  the  time  of  the  formation  of  this  moraine, 
we  still  have  the  small  size  of  these  deposits  to  account  for  before  corre- 
lating them  with  the  great  kettle  moraine,  or  with  a  retreat  and  readvance 
of  the  ice  for  hundreds  of  miles,  such  as  took  place  in  the  Northwest. 

Summary. — Two  liucs  of  rcasouiug  point  toward  two  possible  glaciations 
of  Maine.  The  first  is  based  upon  the  finding  of  two  different  layers  of 
the  till,  possibly  the  till  of  two  different  ice  periods.  No  sedimentary  or 
fossiliferous  beds  have  been  found  between  them,  and  a  better  interpreta- 
tion is  that  they  are  derived  from  two  different  kinds  of  rock — one  local,  the 
other  from  a  distance.  The  second  refers  to  the  finding  of  till  or  glacial 
gravel  overlying  fossiliferous  marine  beds.  It  is  certain  that  the  marine 
beds  in  Maine  overlie  a  stratum  of  till  most  or  all  of  which  was  subglacial. 
They  therefore  were  deposited  late  in  the  Ice  period  of  that  coast,  Avhen  the 
ice  had  receded  far  back  from  its  extreme  limit.  Waiving  all  doubts  as  to 
the  Portland  beds  having  been  caused  by  landslips,  and  assuming  the  most 
favorable  construction,  i.  e.,  that  there  are  terminal  moraines  and  other 
glacial  deposits  overlying  marine  sediments,  we  must  consider  the  signifi- 
cance of  this  assumed  fact.  My  interpretation  of  the  facts  is  that  there  is 
no  proof  that  these  supposed  advances  of  the  ice  were  for  any  but  very 
limited  times  and  distances,  as  is  proved  by  the  small  size  of  the  deposits 
and  the  fact  that  the  glaciation  and  development  of  the  marine  beds  vary 


GLACIAL  SEDIMENTS.  291 

but  little  wlien  we  study  tliem  north  and  south  of  these  moraines.  Local 
advances  and  retreats  of  the  ice  might  be  expected  during  the  decay  of 
the  ice-sheet,  but  they  are  to  be  regarded  as  minor  incidents  of  one 
Griacial  period  rather  than  distinct  periods  worthy  of  a  place  in  geological 
chronology.  The  moraines  that  correspond  to  the  outer  terminal  moraines 
of  the  second  ice-sheet  of  the  Northwest  are  to  be  sought  for  in  the 
Gulf  of  Maine,  liot  along  the  present  coast.  The  so-called  interglacial 
period  of  the  Northwest  was  longer  than  the  intervals  between  the  retreats 
and  readvances  of  the  ice  in  Maine,  so  far  as  the  known  facts  warrant 
conclusions. 

The  significance  and  explanation  of  the  fact,  if  such  it  be,  that  there 
was  but  one  glaciation  are  left  for  future  investigation. 

GLACIAL   SEDIMENTS. 

Under  the  term  "till,"  as  here  used,  is  included  all  matter  transported 
to  its  present  position  by  gdacier  ice.  The  term  "glacial  sediments"  denotes 
all  matter  transported  to  its  present  position  by  streams  of  water  from  the 
melting  ice.  No  doubt  ice  movements  contributed  to  the  transportation  of 
kame  matter.  Yet  clearly  we  have  in  case  of  the  glacial  sediments  a  form 
of  transportation  that  the  till  did  not  undergo.  While  the  till  is  glacier 
drift  simply,  the  former  are  glacial  drift  jilus  water  drift. 

RELATION    OF    WATER    TO    THE    GLACIER. 

Energy  reaches  the  glacier  in  various  forms.  Radiant  energy  comes 
to  it  from  the  sun  and  other  bodies.  Part  is  reflected,  part  is  radiated  and 
lost,  and  part  is  absorbed,  which  is  but  another  way  of  saying-  that  it  is 
transmuted  into  molecular  motion  and  is  expended  in  doing-  work  within 
the  ice,  such  as  melting  it,  raising  its  temperature,  or  aiding  its  flow. 
Molecular  heat  is  communicated  to  the  ice  from  surrounding  bodies  and 
performs  the  same  kinds  of  .work  as  radiant  energy.  Most  of  the  radiant 
heat  comes  from  the  sun,  most  of  the  molecular  heat  from  the  air  and  the 
summer  rains  or  from  the  earth  beneath  the  ice.  The  chief  sources  of  heat 
act  from  above,  and  there  the  most  of  the  melting  and  other  direct  action 
of  heat  takes  place.  The  glacier  is  one  form  of  heat  engine.  From  the 
time  that  heat  aids  in  cementing  the  separate  snow  crystals  into  clear  blue 
ice  up  to  the  time  that  it  resolves  the  ice  back  again  into  granules  and 


292  GLACIAL  GRAVELS  OF  MAINE. 

crystals  and  melts  tliem,  heat  is  inseparably  connected  with  all  the  work  of 
the  glacier.  Water  is  the  heat  transport  of  this  heat  engine.  The  waters 
derived  from  the  melting  ice  flow  along  the  surface  or  gatlier  in  pools  until 
they  find  a  crevasse  down  which  they  can  escape.  In  passing  from  the 
surface  to  the  bottom  of  the  ice  they  carry  heat  with  them.  The  phe- 
nomena of  both  subglacial  and  superglacial  streams  are  largely  determined 
by  the  behavior  of  water  with  respect  to  radiant  and  molecular  heat.  The 
m.ost  important  of  these  relations  are  the  following: 

1.  Water  is  a  poor  conductor  of  molecular  heat,  but  a  good  absorber 
of  radiant  energy. 

2.  Water,  like  all  fluids,  readily  transmits  and  distributes  molecular 
heat  by  means  of  the  convection  currents  so  easily  set  in  motion  within  it. 

3.  The  temperature  of  water  at  its  greatest  density  is  39.1°  F. 

4.  The  temperature  both  of  melting  ice  and  of  freezing  water  (under 
•ordinary  conditions)  is  32°  F, 

5.  The  specific  heat  of  water  is  very  great. 

As  a  result  of  these  properties  of  water,  we  have  water  above  and 
below  the  ice,  and  perhaps  in  some  cases  distributed  everywhere  through 
it  The  glacial  streams  erode  their  banks  and  walls  in  a  manner  peculiarly 
their  own.  Water  is  employed  in  the  hydration  of  the  clay  which  is  formed 
beneath  the  glacier.  Glaciers  have  their  drainage  systems  as  truly  as  does 
the  land,  and  no  other  form  of  stream  erosion  is  so  complex.  In  a  word, 
we  can  not  conceive  of  a  glacier  without  its  system  of  waters.  The  glacial 
sediments  are  as  important  a  matter  of  investigation  as  glaciated  stones 
themselves,  if  we  are  to  detect  former  glacial  periods. 

SIZES  OF  THE  GLACIAL  RIVERS  OF  MAINE. 

Many  considerations  prove  that  the  precipitation  over  a  large  part  of 
ISforth  America  was  very  great  during  glacial  times.  The  occurrence  of 
Lakes  Bonneville  and  Lahontan  in  the  Great  Basin  and  the  observations 
of  Professor  Whitney  in  California  unite  with  the  facts  as  observed  in  many 
other  parts  of  the  country  to  establish  the  general  conclusion. 

Mr.  Walter  Wells,  in  his  report  on  the  water  power  of  Maine,  ^  pointed 
out  manjr  circumstances  favorable  to  a  large  average  precipitation  in  the 

'  Provisional  Report  upon  tlie  Water  Power  of  Maine,  by  Walter  Wells,  Secretary  of  the  Hydro- 
graphic  Survey,  Aiigusta,  327  pp.,  1868,  8°. 


SIZES  OF  GLACIAL  EIVEES.  293 

State  He  computed  the  annual  discharge  of  the  present  rivers  of  Maine 
at  1,229,200,000,000  cubic  feet,  or  3,368,000,000  cubic  feet  daily.  This 
represents  a  precipitation  of  about  3^  feet  per  annum. 

Obviously  in  glacial  times  that  portion  of  Maine  which  was  within  the 
area  of  accumulation  or  ne'v^  had  less  water  discharge  than  the  precipita- 
tion, the  surplus  being  pushed  forward  as  flowing  ice  into  the  zone  of  melt- 
ing. The  position  of  the  n^vd  line  would  determine  the  ratio,  at  any  given 
time,  of  water  discharge  to  the  total  precipitation  over  the  area  now  under 
consideration.  The  location  of  the  uivi  line  during  the  time  of  thickest  ice 
is  uncertain.  The  glaciation  of  the  islands  off'  the  coast  proves  that  at  one 
time  the  ice  advanced  out  into  the  Gulf  of  Maine.  Later,  at  a  time  when 
the  ice  had  retreated  before  the  rising  sea  nearly  or  quite  to  its  coast,  great 
glacial  rivers  were  pouring  into  the  sea  and  were  depositing  in  open  tide 
water  the  largest  marine  deltas  in  the  State.  Here  and  there  we  find  marine 
deltas  south  of  this  line,  proving  that  the  glacial  rivers  had  previously  to 
this  time  been  pouring  into  the  sea  at  various  points  in  the  course  of  the 
retreat  of  the  ice.  At  the  time  the  ice  front  had  receded  as  far  north  as 
the  present  coast  line  the  whole  coast  region  of  Maine  to  a  breadth  of  100 
miles  must  have' been  in  the  zone  of  wastage,  and  either  at  this  time  or 
later  the  whole  State  was  in  this  zone. 

The  melting  of  the  great  body  of  ice  that  covered  the  land  and  was 
continually  renewed  by  flow  from  the  north  would  of  itself  give  a  large 
melting-water  discharge  over  the  zone  of  wastage.  To  this  must  be  added 
the  precipitation  over  the  zones  itself  During  part,  perhaps  all,  of  the 
period  after  the  ice  had  retreated  to  the  present  coast  line,  the  land  stood  at 
less  elevation  in  Maine  than  at  present.  This  would  tend  to  lessen  the  pre- 
cipitation, but  only  in  small  degree.  On  the  other  hand,  during  a  part,  at 
least,  of  this  period  the  sea  advanced  so  far  up  the  St.  Lawrence  and  Chain- 
plain  valleys  that  New  England  was  a  peninsula  or  island  unusually 
accessible  to  moisture  from  the  ocean. 

Whether  we  look,  then,  at  the  great  quantity  of  the  glacial  gravels,  or 
at  the  large  size  of  the  stones  and  bowlders  transported,  or  at  the  broad 
plains  of  valley  drift  which  were  often  deposited  while  ice  still  lingered  to 
the  noi'thward,  or  at  the  local  geographical  conditions,  or  at  the  climate 
prevailing  at  or  about  this  time  in  various  parts  of  the  country,  we  find  that 
evei'ywhere  the  field  phenomena  require  a  larg-e  supply  of  water.     The 


294  GLACIAL  GRAVELS  OF  MAINE, 

precipitation  here  near  the  sea  must  have  been  large,  even  if  diminished 
from  what  it  had  been  during  the  time  of  maximum  glaciation. 

For  these  and  other  reasons  we  postulate  a  larger  water  discharge  in 
Maine  in  late  glacial  times  than  the  present.  The  glacial  rivers  exceeded 
the  present  rivers  in  number  and  had  correspondingl}^  smaller  drainage 
basins.  This  tended  to  diminish  the  size  of  the  individual  rivers,  yet  some 
of  them  have  left  level  plains  one-eighth  to  one-half  mile  wide,  and  appear 
to  have  equaled  or  surpassed  the  discharge  of  the  larger  rivers  of  the  present 
time. 

ZONES  QF  THE  MAINE  ICE-SHEET. 

According  to  the  accounts  of  the  explorers  named  above,  the  interior 
of  Greenland  is  covered  with  snow  fields.  At  the  highest  elevations  if  there 
is  any  melting  it  is  limited,  since  Nordenskjold's  Laps  found  the  surface  dry 
and  powdery.  At  lower  elevations  the  melting  becomes  more  abundant 
and  the  surface  waters  slowly  ooze  through  a  zone  of  slush.  Then  we  find 
pits  filled  with  water,  and,  by  degrees,  the  waters  uniting  to  form  surface 
streams.  Some  of  these  have  been  traced  for  several  miles  and  are  from 
4  to  10  feet  wide.  Still  descending,  we  find  crevasses  appearing,  sometimes 
near  the  nunataks,  at  other  times  where  none  are  visible  but  where  the  ice 
is  probably  flowing  over  a  buried  ridge.  Into  the  crevasses  the  surface 
streams  pour  and  disappear,  escaping  as  subglacial  or  englacial  streams. 
Sometimes  they  pour  with  a  loud  roar  into  small  lakes  within  the  ice. 
Some  of  the  crevasses  are  very  wide  as  well  as  deep,  one  observed  by 
Lieutenant  Peary  being  50  feet  wide.  As  we  approach  the  outer  margin 
the  surface  becomes  indescribably  rough  with  blocks,  hummocks,  and  ridges. 
Here  the  water  derived  from  surface  melting  need  flow  only  a  few  feet  or 
rods  befoie"  plunging  into  the  depths. 

These  observations  give  us  a  general  conception  of  an  ice-sheet  with 
respect  to  its  waters  of  surface  melting.  Over  all  the  region  broken  by 
crevasses  we  have  an  elaborate  system  of  subglacial  and  englacial  streams 
which  receive  the  waters  of  the  short  surface  streamlets.  Above  this  zone 
is  another,  of  superficial  streams,  then  the  area  where  the  snow  absorbs  all 
the  water  of  surface  melting,  which  becomes  progressively  less  as  we  go 
upward. 

Applying  these  principles  to  Maine,  we  note  that  the  average  slope  of 
the  land  southward  is  only  from  3  to  10  feet  per  mile,  much  less  than  is 


ZONES  OF  THE  MAINE  ICE-SHEET.  295 

found  ill  much  of  Greenland.  This  would  favor  a  low  surface  gradient  of 
the  ice-sheet.  The  slope  being  southward  would  favor  a  higher  gradient. 
It  is  probable  that  on  a  uniform  slope  the  gradient  is  chiefly  determined  by 
the  ratio  between  snow  precipitation  and  waste.  During  the  advance  and 
retreat  of  an  ice-sheet  over  transverse  hills  and  valleys  the  surface  gradient 
must  often  change  with  some  corresponding  change  in  the  positions  of  the 
crevasses  and  in  the  boundaries  of  the  zones  of  superficial  and  subglacial 
waters. 

The  ice  flowed  over  Mount  Desert  Island  to  an  unknown  depth.  From 
there  to  Mount  Katahdin  the  distance  is  approximately  110  miles,  and  they 
are  nearly  in  the  same  lines  of  glacial  motion.  Prof  C.  H.  Hitchcock,  in 
his  report  on  the  geology  of  Maine,  estimated  that  the  top  of  Mount  Katah- 
din rose  above  the  ice  surface.  I  visited  the  mountain  in  1870  and  found 
fossiliferous  drift  fragments  to  within  a  few  hundred  feet  of  the  summit, 
just  as  Professor  Hitchcock  did, -but  there  has  been  so  much  surface 
weathering  and  sliding  toward  the  top  that  drift  ddbris  would  long  since 
have  disappeared,  even  if  it  had  once  been  there.  However,  without 
insisting  on  the  doubt,  if  we  assume  the  highest  limit  of  the  ice  at  4,500 
feet  at  Katahdin  and  1,500  feet  at  Green  Mountain,  Mount  Desert,  we  have 
a  surface  gradient  of  27  feet  per  mile.  If  the  gradient  was  as  moderate  as 
this,  or  near  it,  we  have  reason  to  estimate  the  zone  of  subglacial  waters 
as  pretty  broad. 

The  western  part  of  Maine  must  haA'e  been  overflowed  by  the  ice 
from  the  St.  Lawrence  Valley  and  Hudson  Bay.  How  far  east  this  north- 
ern ice  overflowed  Maine  is  at  present  uncertain.  Without  assuming  the 
correctness  of  Mr.  Chalmers's  hypothesis  of  a  divergent  flow  in  eastern 
Quebec  and  New  Brunswick  as  applying  to  Maine,  we  must  at  least  con- 
sider it  a  possibility.  Obviously  the  breadth  of  the  zone  of  subglacial 
waters  of  an  ice-sheet  fed  from  the  far  North  will  be  much  greater  than  of 
a  local  ice-sheet  covering  the  peninsula  south  of  the  lower  river  and  Gulf 
•of  St.  Lawrence.  Until  the  doubt  as  to  the  condition  of  northeastern 
Maine  is  removed  it  will  be  unsafe  to  attempt  an  estimate  of  the  position 
of  the  n^ve  line  at  any  stage  of  the  glaciation. 


296  GLACIAL  GRAVELS  OF  MAINE. 

ENGLACIAL    STREAMS. 

Recent  observations  of  the  Alaskan  glaciers  warrant  the  belief  that 
englacial  streams  are  sometimes  of  g-eological  importance,  or  perhaps  it 
might  be  better  stated  that  the  englacial  portions  of  streams  that  are  sub- 
glacial  or  snperglacial  for  the  rest  of  their  course  have  helped  in  the 
development  of  the  glacial  sediments.^ 

It  is  evident  that  any  conditions  that  prevent  the  formation  of  crevasses 
in  the  lower  part  of  the  ice  will  hinder,  if  not  prevent,  the  formation  of  sub- 
glacial  tunnels,  at  least  as  conduits  for  waters  of  surface  melting.  Where 
crevasses  reach  only  part  of  the  distance  down  to  the  bottom  of  the  ice, 
the  superficial  water  would  often  form  an  englacial  channel  along  the  bot- 
tom of  the  crevasses.  The  collapse  or  blocking  of  a  subglacial  tunnel 
would  cause  the  water  to  rise  and  escape  superglacially,  or  in  case  of  cre- 
vasses it  would  form  a  new  channel  either  at  the  bottom  of  the  ice  or  above 
it  englacially.  In  a  shrinking  glacier  the  melting  of  the  ice  forming  the 
roof  of  an  englacial  tunnel  would  leave  it  as  a  snperglacial  stream.  The 
stream  reported  by  Russell  as  rising  on  the  Lucia  glacier  where  it  flows 
past  a  nunatak  would  appear  to  have  formerly  had  an  englacial  channel  at 
this  place,  now  become  superficial  by  melting.  The  situation  suggests 
that  the  course  of  glacial  rivers  in  such  relations  ma)^  have  been  deter- 
mined by  the  fact  that  the  ice  of  the  deep  valley  at  the  sides  of  the  nunatak 
was  so  compressed  laterally  as  it  parted  and  flowed  around  the  hill  that  the 
basal  ice  was  little  broken  by  crevasses.  Crevasses  would  naturally  form 
over  the  top  or  higher  flanks  of  the  hill,  but  would  not  reach  below  some 
point  on  the  hillside.  These  shallow  crevasses  were  utilized  by  the  stream 
as  part  of  its  channel. 

Englacial  streams  and  channels  of  the  ice-sheet  may  have  performed 
two  different  offices. 

First,  they  may  have  amassed  glacial  sediments  directly  from  the  ice. 
Wbether  we  consider  them  of  importance  as  gatherers  of  glacial  sediments 
will  largely  depend  on  our  conception  of  the  distribution  of  the  debris  in 
the  ice.  The  only  way  such  streams  could  directly  collect  glacial  sediments 
would  be  by  melting  the  ice  around  the  debris  and  transporting  it.     The 

'  Prof.  I.  C.  Russell,  Nat.  Geog.  Mag.,  toI.  3,  pp.  106,  107,  May,  1891.  Am.  Jour.  Sci.,  3d  aerieSr 
vol.  43,  p.  180,  March,  1892.     Also  Prof.  G.  F.  Wright,  Ice  Age  in  North  America,  p.  63,  1889. 


SUBGLACIAL  AND  ENGLAOIAL  STREAMS.  297 

higher  the  eng-lacial  debris  rose  in  the  ice  the  more  would  the  supei-ficial 
and  englacial  streams  be  able  to  collect.  Those  who  believe  the  englacial 
matter  to  have  been  strictly  basal  will  not  admit  that  either  class  of  streams 
would  be  able  to  gather  much  sediment  until  their  beds  sank  nearly  to  the 
ground. 

Second,  the  englacial  channels  were  often  simple  conduits  for  streams 
otherwise  subglacial.  As  such,  their  mission  may  have  been  simply  to 
protect  the  ground  moraine  from  erosion,  or  glacial  gravels  may  have  been 
deposited  in  them.  In  the  last  case  the  stratification  of  the  sediments 
would  be  generally  obliterated  by  the  melting  of  the  subjacent  ice. 

In  Maine  I  have  discovered  numerous  places  in  the  line  of  long  glacial 
rivers  where  the  ground  moraine  is  less  eroded  than  in  the  case  of  some  of 
the  short  hillside  eskers,  as,  for  instance,  at  The  Notch,  in  Garland.  Both 
to  the  north  and  south  the  stratification,  etc.,  are  consistent  with  the 
hypothesis  that  these  were  subglacial  rivers  through  most  of  their  course. 
How  can  we  account  for  so  little  erosion  of  the  ground,  moraine  ?  At  one 
time  I  considered  these  places  strong  evidence  that  the  osar  rivers  were 
superficial  as  a  whole,  but  it  must  now  be  admitted  that  they  may  imply 
only  an  englacial  or  superficial  course  of  a  subglacial  river  for  a  short 
portion  of  its  length.  Thus  in  the  jaws  of  the  naiTOw  pass  of  The  Notch, 
Garland,  the  basal  ice  may  have  been  so  solid  that  for  a  mile  or  more  a 
subglacial  river  was  forced  to  rise  into  or  on  the  ice.  In  1888  I  suggested 
that  such  accidents  might  not  be  uncommon,  but  without  observational 
basis  for  the  idea.  Without  insisting  on  close  analogies  between  the 
Alaskan  glaciers  and  the  ice-sheet,  we  must  at  least  consider  englacial 
streams  as  one  of  the  forms  of  a  glacial  water  action,  and  probably  an 
important  one. 

DIRECTIONS   OF   SUBGLACIAL   AND   ENGLACIAL   STREAMS   UNDER   EXISTING 

GLACIERS. 

The  recoi'ded  observations  bearing  on  this  subject  are  too  few  to 
permit  generalization.  The  courses  of  only  a  few  of  the  subglacial  rivers 
are  more  than  approximately  known.  At  the  terminal  enlargement  of 
the  glacier  of  the  Rhone,  the  courses  of  the  subglacial  streams  have 
been  mapped,  and  it  is  known  that  some  of  them  flow  transversely  to  the 
direction  of  ice  flow.     But  this  takes  place  longitudinally  and  where  the 


298  GLACIAL  GKAVELS  OF  MAINE. 

water  wonki  find  unusual  facilities  for  flowing-  in  almost  any  direction  by  zig- 
zagging along  crevases.  We  can  not  therefore  consider  tins  case  typical  of 
the  behavior  of  the  subglacial  waters  under  thicker  and  less  broken  glaciers. 

We  know  that  the  subglacial  streams  of  ordinary  valley  glaciers  must 
flow  approximately  parallel  to  the  ice,  for  the  very  obvious  reason  that  they 
are  confined  between  the  sides  of  the  valleys  and  can  not  wander  out  of 
them.  But  such  a  statement  adds  nothing  to  our  knowledge  of  glacial  con- 
ditions and  can  not  satisfy  us.  We  wish  to  know  more  of  the  laws  that 
govern  the  formation  and  maintenance  of  subglacial  channels.  For  instance, 
in  the  case  of  glaciers  flowing  in  meandering  valleys,  it  is  well  known  that 
the  line  of  swiftest  ice  flow  is  a  curve  more  crooked  than  the  axis  of  the 
glacier.  Are  there  conditions  under  which  a  coi'responding  deflection  of 
the  subglacial  rivers  takes  place  along  the  lines  of  swiftest  motion,  or  do 
they  follow  a  less  crooked  course  than  the  axis  of  the  glacier"?  This  and 
many  similar  questions  need  to  be  answered  observationally  before  we  can 
understand  the  drainage  systems  of  existing  glaciers,  still  less  of  extinct 
ice-sheets. 

We  ma}'-  form  two  verj^  diff'erent  conceptions  of  the  relation  of  the  ice 
of  the  glacier  to  its  waters. 

First,  we  may  consider  the  ice  as  static,  like  the  stationary  land.  The 
waters  falling  on  the  earth  cut  into  it  valleys  and  canyons,  as  do  the  super- 
ficial streams  on  the  ice.  They  penetrate  its  pores  and  crevices,  as  glacial 
waters  do  the  snow  and  ice.  They  enlarge  the  subterranean  passages  into 
watercourses  like  the  subglacial  and  englacial  channels,  and  in  both  land 
and  glacier  these  internal  channels  often  overflow  on  the  surface  as  foun- 
tains. In  short,  the  waters  falling  on  the  land,  though  often  emplo}'ing 
different  forces,  yet  in  the  end  achieve  substantially  the  same  results  as  the 
superficial  waters  of  the  glacier.  But  in  all  this  the  land  is  stationary;  it  is 
simply  obsti'uctive,  holding  back  the  water  or  modifying  its  flow  by  friction 
or  direct  pressure.  So  also  glacial  ice  as  static  is  nothing  but  an  obstruc- 
tion to  its  waters.  But  for  the  ice  the  waters  would  follow  the  drainage 
slopes  of  the  land;  whereas  the  ice,  by  simply  standing-  in  the  way,  often 
forces  the  water  to  follow  crevasses  or  other  channels  along  lines  very  dif- 
ferent from  the  land  slopes.  In  fact,  on  this  conception  the  ice  is  simply 
regarded  as  a  rock  and  its  internal  water  system  a  part  of  the  subterranean 
drainao'e. 


SUBGLACIAL  AND  ENGLACIAL  STEEAMS.  299 

But  second,  we  may  consider  the  ice  of  glaciers  as  in  motion.  While 
portions  of  the  land  are  being  upheaved  the  rising  terranes  are  brought 
under  the  sharper  rasp  of  swifter  streams,  the  earth  by  its  internal  move- 
ments thus  guiding  the  development  of  the  erosion.  In  like  manner  we 
may  view  the  glacier  as  in  motion,  a  soi't  of  organism  having  its  internal 
motion  so  far  determined  by  its  environments  that  it  has  a  systematic  devel- 
opment, and  each  part  of  the  ice  must  be  considered  not  alone  with  respect 
to  the  forces  now  acting  on  it,  but  as  having  a  history,  and  as  often  retain- 
ing the  forms  or  structures  it  obtained  long  before.  This  is  obviously  true 
of  the  banded  structure  and  other  features  visible  on  the  surface,  and  ought 
equally  to  be  true  of  unseen  parts  Thus  if  the  basal  ice  is  hollowed  out 
by  the  water  that  falls  down  a  crevasse  at  a  moulin,  the  forward  motion  of 
the  ice  will  cause  each  successive  portion  of  the  ice  as  it  advances  to  that 
place  to  be  also  hollowed — the  mechanical  equivalent  of  a  forward  prolon- 
gation of  a  series  of  hollows  that  together  make  a  tunnel  but  are  subse- 
quently modified  by  the  tendency  of  the  stream  to  enlarge  the  channel  and 
of  the  antagonistic  upwai'd  flow  of  the  ice  to  cause  its  collapse.  Now  if 
.  the  ice,  having  thus,  so  to  speak,  gotten  the  stream  in  its  power,  shall 
continue  to  carry  it  along  the  same  tunnel  prolonged  by  the  ice  movement, 
we  must  consider  the  ice  as  having  more  than  obstructive  power.  By 
virtue  of  its  motion  it  so  exerts  its  obstructive  power  in  the  direction  or 
along  the  line  of  its  motion,  that  it  can  be  said  to  have  a  constructive  power 
to  help  build  its  own  tunnels  and  determine  their  courses  and  develop- 
ment. The  moving  ice  tends  to  the  maintenance  of  all  subglacial  and 
englacial  tunnels  parallel  to  its  flow,  while  the  water  with  equal  pertinacity 
strives  to  follow  the  slopes  of  the  underlying  land.  When  the  movement 
pushes  the  tunneled  ice  over  i-ising  gi'ound  the  water  bides  its  time,  and  at 
the  first  eligible  transverse  crevasse  it  steals  off  sidewise  toward  the  lower 
ground.  The  ice  moves  onward  and  prolongs  the  now  unused  tumiel 
until  it  becomes  filled  by  subglacial  till  or  disappears  by  the  collapse  of  its 
sides  and  roof.  On  this  conception  the  actual  course  of  a  subglacial  or 
englacial  river  is  the  resultant  of  two  forces  which  may  or  may  not  be 
antagonistic,  viz,  the  movement  prolonging  the  tunnel  in  its  own  direction, 
and  the  water  tending  to  follow  the  slopes  of  the  underlying  land  wherever 
practicable.  In  this  discussion  we  assume  the  tunnels;  we  do  not  account 
for  their  origination. 


300  GLACIAL  GEAVELS  OF  MAINE. 

It  is  a  matter  of  observation  that  even  small  surface  streams  generally 
find  no  difficulty  in  flowing  into  crevasses  and  finding  exit  by  si;bglacial  or 
englacial  channels,  whereas  waters  flowing  against  the  sides  of  glaciers  are 
usually  dammed  by  the  ice  until  glacial  lakes  accumulate.  One  of  the  best 
known  of  such  lakes  is  the  Marjelen  See  in  Switzerland,  found  where  the 
Great  Aletsch  glacier  flows  past  the  mouth  of  a  small  lateral  valley.  The 
lake  is  about  fi  mile  long  and  one-fourth  as  wide,  its  longer  axis  being  at 
right  angles  to  the  glacier.  The  water  of  the  lake  is  warmed  by  the  sim, 
and  also  receives  the  water  of  several  small  streams  which,  during  several 
months  of  the  year,  have  been  warmed  on  land  bare  of  ice.  Many  small 
icebergs  fall  from  the  glacier  into  the  water  and  float  about  the  lake. 
Obviously  the  water  of  39°  must  sink  to  the  bottom,  below  the  reach  of 
the  smaller  bergs,  and  it  will  slowly  melt  away  the  side  of  the  glacier. 
The  fall  of  the  berglets  is  jDrobably  diie  to  the  melting  of  the  ice  beneath 
them.  But  although  the  side  of  the  glacier  is  thus  undermined  as  it  flows 
past  the  lake,  it  is  not  melted  away  sufficiently  to  prolong  a  channel  down 
the  valley  between  the  ice  and  the  mountain.  It  is  only  after  several  years 
that,  to  use  Lyell's  language,  owing  to  ' '  chang  es  in  the  internal  stiiicture  of 
the  glacier,"  "rents  or  crevasses  in  the  ice  open  and  give  passag'e  to  the 
waters."  The  pressm-e  is  so  great  that  the  discharge  takes  place  with  a 
loud  roaring-  rush  of  waters  along  the  central  parts  of  the  glacier.  That  it 
is  along  the  channel  of  a  subglacial  river  is  proved  by  the  fact  that  toward 
the  lower  end  of  the  glacier  a  great  quantity  of  water  spouts  upward 
through  the  crevasses  and  escapes  down  the  steep  slope  on  the  surface  of 
the  ice.  It  is  evident  that  at  the  time  of  the  discharge  there  is  a  large 
opening  into  the  permanent  waterways  of  the  glacier,  but  for  some  reason 
the  inflowing  streams,  though  in  summer  warmed  on  land  bare  of  ice,  are 
not  able  to  maintain  the  channel.  It  soon  closes,  perhaps  by  being  pushed 
past  the  mouth  of  the  lateral  valley,  and  the  lake  is  not  able  again  to  force 
an  outlet  till  after  the  lapse  of  several  years.  In  the  Alps,  in  Alaska,  and 
in  most  mountainous  countries  now  glaciated,  are  many  similar  lakes 
formed  in  valleys  lateral  to  glaciers,  and  the  Parallel  Roads  of  Gleni-oy, 
Scotland,  and  many  similar  raised  beaches  found  in  Sweden  and  Norway 
mark  the  sites  of  ancient  but  now  extinct  glacial  lakes  of  this  class. 

The  inference  follows  that  streams  flowing  transversely  against  the 
sides  of  glaciers  do  not  readily  form  subglacial  outlets  beneath  them.     The 


SUBGLACIAL  AND  ENGLAOIAL  STREAMS.  301 

exceptions  to  this  rule  are  near  the  distal  extremities  of  glaciers  where  the 
ice  is  much  shattered. 

Various  physical  causes  can  be  assigned  for  the  discharge  of  lateral 
glacial  lakes.  Thus  in  the  course  of  climatic  changes  or  cycles  it  may 
happen  from  time  to  time  that  crevasses  open  in  new  places,  or  they  may 
open  wider  and  extend  farther  than  usual  toward  the  side  of  the  g-lacier,  or 
there  may  be  a  larger  supply  of  warm  water  in  the  lake  to  enable  it  to 
melt  its  way  farther  into  the  glacier  till  an  opening  is  made  into  a  crevasse 
connecting  with  a  subglacial  or  englacial  tunnel.  So,  too,  by  reason  of  its 
greater  specific  gravity  the  water  tends  to  float  the  ice  in  contact  with  it, 
the  buoyancy  of  the  water  being  resisted  not  only  by  the  weight  of  the 
ice  next  the  lake,  but  also  by  all  the  ice  cohering  to  it.  Again,  the  j^ressure 
of  the  water  is  directly  tending  to  rupture  the  ice.  While  these  and  other 
physical  agencies  are  operative  in  the  discharg-e  of  glacial  lakes,  obviously 
it  is  only  by  test  and  observation  that  we  can  determine  the  causes  in  any 
particular  case. 

While,  then,  the  existence  of  so  many  lakes  lateral  to  glaciers  is  proof 
that  waters  can  not  find  basal  passage  under  glaciers  in  all  directions 
except  under  the  most  favorable  conditions,  yet  the  fact  of  occasional  dis- 
charge beneath  the  ice  can  be  cited  in  favor  of  the  hypothesis  that  subgla- 
cial rivers  can  luider  some  conditions  flow  transversely  to  the  ice  of  eveii 
thick  glaciers  as  well  as  the  waters  from  glacial  lakes. 

While  the  conclusions  that  can  at  present  be  drawn  from  existing  gla- 
ciers are  rather  meager  and  demand  further  investigation  as  to  the  courses 
of  the  internal  streams,  yet  incidentally  they  fall  in  line  with  many  other 
indications  as  to  the  streams  of  the  ice-sheet.  The  osars  of  Maine  are  often 
for  considerable  distances  more  or  less  transverse  to  the  existing  glacial 
scratches,  as  well  as  to  the  bowlder  trains  and  elongated  drumlins,  and 
therefore  probably  transverse  to  the  direction  of  glacial  motion.  The 
known  instances  of  the  subglacial  flow  of  water  transversely  to  the  ice  flow, 
admitting  the  least  allowable  weight  to  analogies,  indicate  that  the  trans- 
verse direction  of  the  osars  can  not  be  held  incompatible  with  their  having 
been  subarlacial. 


302  GLACIAL  GRAVELS  OF  MAINE. 

INTERNAL    TEMPERATURES    OF    ICE-SHEETS. 

Surface  rocks  and  soils  experience  great  changes  in  temperatures,  but 
as  we  descend  into  the  earth  we  pass  beyond  the  influence  of  the  seasons 
and  reach  a  point  of  invariable  temperature.  It  has  been  computed  that  in 
temperate  zones  this  point  lies  at  an  average  depth  of  about  50  feet,  vary- 
ing greatly  according  to  the  local  conditions.  In  far  northern  countries 
where  there  is  little  snow  the  earth  is  permanently  frozen  after  we  reach  a 
depth  of  a  few  feet. 

Without  assuming  the  causes  of  the  ice  epoch  we  can  at  least  assume 
practically  Arctic  conditions  as  then  prevailing  over  the  region  overrun  by 
the  ice-sheet.  It  is  important  to  know,  if  possible,  what  temperatures  pre- 
vailed within  that  vast  body  of  snow  and  ice.  Was  that  4,000  feet  or  more 
of  ice  a  rock  which,  like  other  rocks,  had  beneath  its  surface  a  level  of 
invariable  temperature?  If  so,  at  what  depths,  and  what  was  the  tempera- 
ture!    Where  did  the  isogeotherm  of  32°  lie  in  winter  and  in  summer'? 

The  only  tests  made  of  the  temperatui-e  of  glaciers  have  been  made 
near  their  distal  extremities,  where  both  the  ice  and  glacial  waters  are 
reported  to  have  a  nearly  constant  temperature  of  32°.  No  observations 
appear  to  have  been  made  of  the  interior  temperatures  of  the  n^v^,  and 
we  can  arrive  at  only  an  approximate  estimate  by  reasoning  from  some 
known  facts.  In  such  an  investigation  we  have  to  depend  chiefly  on  the 
following  physical  properties  of  water  and  ice: 

1.  AVater  has  a  very  high  specific  heat. 

2.  Water  and  ice  are  poor  conductors  of  molecular  heat,  especially  ice 
in  the  form  of  snow. 

3.  Water  freezes  without  change  of  temperature  at  the  surface  of 
freezing  so  long  as  any  water  remains  unfrozen,  the  latent  heat  of  liquidity 
being  given  up  in  the  act  of  solidifying. 

4.  Ice  melts  with  contraction  of  volume  and  without  change  of  tem- 
perature at  the  surface  of  melting  so  long  as  any  portion  remains  unmelted. 

These  properties  account  for  the  remarkable  power  the  glacier  has  of 
regulating  its  own  temperatures.  The  heat  of  summer  or  of  the  day  first 
raises  the  mass  to  32°,  and  then  the  surplus  is  expended  in  melting  some  of 
the  ice,  without  change  of  temperature.  In  winter  or  at  night  the  surface 
temperature  of  dry  ice  falls  like  that  of  other  surface  rocks,  except  that  the 


INTERNAL  TEMPEEATURBS  OF  ICE-SHEETS.  30B 

waste  is  probably  slower,  owing'  to  its  low  conducting  power  and  high  specific 
heat.  The  point  in  the  interior  where  we  first  reach  an  invariable  tempera- 
ture lies  nearer  the  surface  of  ice  than  in  other  rocks.  In  addition  to  these 
properties  which  make  changes  of  temperature  of  the  ice  mass  take  place 
slowly,  the  glacier  has  at  its  command  another  most  important  means  of 
maintaining  and  regulating  its  temperature.  It  is  known  that  there  is  a 
large  amount  of  surface  melting  over  much  or  all  of  the  n^v^,  axid  progres- 
sively more  as  we  approach  the  distal  extremity.  A  large  amount  of  water 
is  during  the  day  and  summer  stored  up  in  tlie  snow  of  the  n^v^  and  in 
that  contained  in  crevasses;  water  is  always  found  in  the  larger  subglacial 
channels,  often  also  in  surface  pools  and  crevasses  without  outlet  beneath 
into  the  tunnels,  and  in  internal  cavities  in  the  granulated  ice  near  the  surface. 
The  moment  the  temperature  at  any  wet  place  tends  to  fall  below  32",  some 
of  this  water  is  frozen  and  the  temperature  maintained.  The  glacial  waters 
thus  serve  an  important  purpose  in  storing  up  heat  when  there  is  an  excess 
above  32°  and  in  giving  it  out  again  when  there  is  a  deficiency.  Those 
parts  of  glaciers  at  a  distance  from  water  must  fall  in  temperature  during 
the  cold  of  night  and  of  the  winter,  just  like  other  rocks. 

The  net  result  is  that  the  wet  parts  of  the  glacier,  i.  e.,  all  the  region 
of  surface  melting  extending  from  the  distal  extremities  well  up  into  the 
nevd,  have  the  nearly  constant  temperature  of  32°.  In  summer  the  isogeo- 
therm  of  32°  rises  to  the  top  of  the  glacier  in  all  this  region,  or  rather,  the 
isogeothermal  stratum  of  32°  includes  the  whole  glacier  from  the  bottom  to 
the  top.  In  winter  the  upper  limit  of  this  stratum  sinks  beneath  the  sur- 
face an  undetermined  and  varying  distance. 

As  we  go  above  the  zone  of  wastage  into  that  of  accumulation  it 
becomes  uncertain  what  are  the  internal  temperatures  of  the  snow  fields. 
The  addition  of  new  layers  of  snow  is  constantly  pressing  down  into  the 
interior  of  the  mass  the  older  layers,  many  of  which  would  have  had  a 
temperature  far  below  zero  when  covered,  and  must  abstract  a  great  amount 
of  lieat  from  the  interior  of  the  ne'vd  The  heat  of  summer  could  not 
directly  penetrate  dry  granular  snow  so  far  as  it  could  clear  solid  ice. 
Above  the  linnt  of  appreciable  surface  melting  it  is  doubtful  if  the  heat  that 
comes  from  above  can  pass  in  large  quantity  far  down  into  the  snow. 
Where  the  snowfall  was  very  great  during  the  intense  cold  of  winter  and 
at  high  elevations,  it  might  happen  that  the  heat  of  summer  could  not  pass 


304  GLACIAL  GRAVELS  OF  MAINE. 

clown  to  ttie  bottom  of  the  previous  winter's  snow  so  as  to  raise  it  all  to  32°. 
If  so,  tliis  very  cold  snow,  sinking  down  towai'd  the  ground  beneath  the 
pressure  of  later  snows,  would  cause  a  temperature  below  32°  to  pi'evail 
•downward  to  some  unknown  depth,  where  the  heat  of  the  earth  would  just 
suffice  to  overcome  it  and  cause  a  temperature  of  32°.  The  isogeotherm  of 
32°  might  here  lie  not  far  above  the  ground,  or  even  beneath  it. 

It  has  sometimes  been  assumed  that  because  the  surface  portions  of 
the  highest  parts  of  the  ndv^  were  found  diy  and  powdery  there  is  no 
melting  in  that  region.  I  am  satisfied  that  inferences  founded  on  observa- 
tion of  only  the  surface  of  snow  are  to  be  received  with  caution.  I  have 
seen  several  places  in  the  Rocky  Mountains  where  water  of  surface  melt- 
ing filtered  down  through  the  snow,  leaving  the  surface  dry  and  powdery 
and  with  no  sign  of  surface  melting,  or  with  only  a  thin  crust  which 
the  wind  soon  blew  away.  In  one  such  case  a  drift  about  20  feet  deep 
had  foi'med  on  the  frozen  ground.  Soon  after  a  warm  wind  melted  con- 
siderable snow,' and  then  followed  two  weeks  of  ver}-  cold  weather,  when  the 
mercury  stood  at  or  below  zero  most  of  the  time.  The  temperature  of  the  air 
was  still  below  the  freezing  point  when  an  excavation  accidentally  revealed 
the  fact  that  the  lower  part  of  the  diift  to  a  depth  of  4  feet  was  moist  and 
part  of  it  was  almost  slush.  No  stream  or  spring  was  here  and  the  earth 
beneath  was  frozen.  It  was  evident  that  the  moisture  was  due  to  water  of 
surface  melting  that  had  seeped  down  through  the  snow,  leaving  no  sign  of 
its  former  presence  to  the  eye  of  an  unguarded  observer.  No  limit  can  be 
set  to  the  distance  that  water  will  pass  into  snow  as  into  sand,  provided  it 
does  not  reach  a  stratum  having  a  temperature  below  the  freezing  point. 

Summary. — AH  tliosc  parts  of  glaciers  where  there  is  enough  melting  to 
furnish  water  and  store  more  of  it  in  summer  than  freezes  in  winter  have 
the  constant  temperature  of  melting-  ice  irrespective  of  season.  Over  all 
the  zone  of  waste  the  glacier  has  the  internal  temperature  of  32°,  while  the 
temperature  of  the  dry  surface  ice  varies  with  the  seasons,  but  can  never 
rise  above  32°.  Under  this  part  of  an  ice-sheet  the  bottom  of  the  ice  is 
never  frozen  to  the  ground,  but  is  bathed  by  at  least  a  molecular  film  of 
water.  The  ground  and  the  subglacial  till  are  here  unfrozen.  As  we  go 
above  into  the  area  of  accumulation  the  internal  and  basal  temperatures 
.are  variable  and  uncertain. 


GLACIAL  SEDIMENTS,  305 

BASAL  WATERS  OF  ICE-SHEETS. 

Ice-sheets  covering  all  the  land  obviously  receive  beneath  them  no 
water  from  adjoining  land  bare  of  ice. 

The  waters  found  beneath  ice-sheets  are  due  to  various  causes,  as 
follows: 

1.  Water  of  surface  melting  that  has  gotten  beneath  the  ice  through 
crevasses.     This  is  by  far  the  largest  source  of  subglacial  waters. 

2.  Basal  melting  due  to  the  internal  heat  of  the  earth.  This  normally 
occurs  under  all  the  parts  of  the  glacier  and  neve  having  a  basal  tempera- 
ture of  32°.  Assuming  the  correctness  of  Taine's  estimate  of  the  internal 
heat,  the  annual  basal  melting  equals  a  stratum  having  a  thickness  of  0.36 
inch  covering  an  area  equal  to  that  of  the  ice.  This  might  be  modified  by 
the  circulation  of  subterranean  waters. 

The  fact  that  the  subglacial  rivers  continue  to  flow  during  the  winter 
has  sometimes  been  urged  as  a  proof  of  basal  melting.  But  it  is  known 
that  in  winter  the  larger  crevasses  become  filled  with  a  large  amount  of 
snow,  even  down  to  the  distal  extremity  of  the  glacier.  This  snov\r  partly 
melts,  partly  sinks  into  the  depths,  where  it  is  only  slowly  consohdated  to 
ice.  So  also  in  the  zone  of  surface  slush  there  is  a  large  quantity  of  snow 
capable  of  holding  water  like  a  sponge.  It  is  certain  that  there  is  a  large 
amount  of  unconsolidated  snow  on  all  large  glaciers  or  within  their  wounds 
that  is  saturated  with  water  at  the  end  of  summer.  These  granular  masses 
act,  like  the  soils  and  other  porous  strata,  as  reservoirs  to  moderate  the 
flow,  and  thus  they  hold  back  the  water  till  long  after  surface  melting  has 
ceased  for  the  season.  Waters  of  springs  issuing  from  the  earth  would 
continue  to  flow  during  the  winter.  We  can  thus  account  for  large  streams 
continuing  to  flow  from  glaciers  during  the  winter  irrespective  of  basal 
melting  from  the  internal  heat  of  the  earth.  Such  melting  in  winter  must 
be  proved  b}^  other  evidence  than  the  mere  presence  of  water  beneath  the 
glacier  at  that  season. 

3.  Basal  melting  caused  by  friction  of  the  ice  against  its  bed. 

In  connection  with  the  friction  of  the  ice  against  the  underlying  rocks 
and  till,  we  may  also  consider  the  friction  of  dcibris  held  in-  the  ice  against 
the  bed  or  of  one  piece  against  another.  When  we  consider  the  great  amount 
of  rock  that  was  planed  off  beneath  the  ice-sheet  and  reduced  to  rock  flour 
or  broken  into  fragments,  we  must  conclude  that  the  doing  of  so  great  an 
MON  xxxiv 20 


306  GLACIAL  GEAVELS  OF  MAINE. 

amount  of  mechanical  work  was  inevitably  accompanied  by  a  considerable 
development  of  heat  from  friction.  Its  quantity  would  depend  on  many 
variables,  such  as  the  coefficient  of  friction  of  the  ice  against  different  kinds 
of  rock,  the  pressure  and  rate  of  motion  of  the  ice,  the  amount  of  englacial 
matter,  etc.  It  is  well  known  that  beneath  landslides  and  avalanches  con- 
siderable frictional  heat  is  developed.  Whether  the  heat  generated  by  the 
slower  motion  of  the  snow  and  ice  will  cause  basal  melting  depends  on  the 
basal  temperature  of  the  mass.  Where  available  for  melting,  heat  from  this 
cause  might  considerably  augment  the  basal  waters,  but  the  quantity  is 
unknown. 

4.  Basal  melting  due  to  heat  transmitted  from  above  through  the  ice. 

Croll's  theory  of  glacial  motion  seems  to  involve  the  hypothesis  that 
heat  can  be  transmitted  from  a  particle  of  water  to  a  particle  of  ice  without 
a  difference  of  temperatm-e  to  act  like  the  electromotive  force  to  di-ive  it. 
Without  .involving  ourselves  in  dynamical  questions,  we  can  for  the  time  con- 
sider the  ice  as  static,  and  assume  that  the  passage  of  molecular  heat  in  it  is 
from  particle  to  particle  by  the  process  of  conduction  from  where  there  is  a 
higher  to  a  lower  temperature.  It  follows,  since  all  the  lower  portions  of 
glaciers  have  the  temperature  of  32°,  that  the  heat  contained  in  the  ice  can 
not,  unless  pressure  changes  the  melting  point,  pass  out  of  one  part  of  the 
ice  to  produce  melting  of  another  part  of  the  same  body  of  ice.  Omitting 
from  the  present  discussion  the  questions  involved  in  the  varying  melting 
point  of  ice  under  varying  pressures,  we  are  justified  in  the  conclusion  that 
molecular  heat  from  the  surface  will  be  conducted  downward  until  the  tem- 
perature of  all  the  mass  is  at  32°,  and  then  no  more  can  pass,  for  the  ten- 
sion, to  use  the  electrical  term,  is  then  equally  high  in  every  part.  But  in 
the  form  of  ether  vibrations  energy  can  penetrate  the  ice  irrespective  of 
temperature.  The  rougher  and  more  granular  condition  of  the  ice  near  the 
surface  indicates  that  most  of  the  radiant  heat  is  absorbed  soon  after  passing 
into  the  ice — i.  e.,  is  converted  into  molecular  heat  and  causes  melting  at  a 
multitude  of  places.  The  reflections  from  the  surfaces  of  these  cavities 
containing  water  causes  the  opaque  and  granular  appearance  of  surface  ice. 
But  it  is  well  known  that  the  words  "transparent"  and  "opaque"  are  rela- 
tive terms,  referring  only  to  visual  rays,  not  to  all  the  waves  of  ether  energy. 
It  seems  probable  that  the  rays  capable  of  producing  photographic  effects 
on  silver  salts,  and  all  the  rays  visual  to  the  eye,  are  absorbed  by  water 


BASAL  WATERS  OF  ICE  SHEETS.  307 

and  ice  before  reaching  a  depth  of  many  hundred  feet.  But  there  are 
abyssal  animals  in  the  sea  far  below  those  depths,  and  they  have  eyes,  prov- 
ing that  even  at  such  great  depths  ether  waves  of  low  refrangibility  are  not 
absorbed  by  the  water.  The  passage  of  radiant  energy  from  the  sun  and 
stars  into  the  ice  will  be  affected  in  considerable  degree  by  the  condition  of 
the  ice  surface.  The  rougher  and  more  broken  the  surface  ice,  the  larger 
the  proportion  that  will  be  refracted  and  reflected  and  radiated  outward  and 
lost  or  absorbed  in  the  surface  ice.  A  residue  remains  of  rays  not  absorb- 
able by  the  ice  or  absorbed  only  after  traveling  a  long  distance  in  it,  which 
may  be  transmitted  through  it  till  they  come  to  englacial  d(^bris  or  to  the 
ground.  Here,  being  absorbed  in  part,  they  become  changed  to  molecular 
heat  and  melt  the  adjacent  ice.  While  the  passage  of  stellar  and  solar 
radiations  to  considerable  depths  in  the  ice  is  probable,  the  quantity  is 
unknown  and  has  not  been  proved  by  observation.  If  we  could  prove  that 
any  considerable  amount  of  heat  was  thus  transmitted  through  the  ice,  it 
would  greatly  help  to  account  for  the  accumulation  of  drumlins  and  the 
glacial  gravels  and  the  dropping  of  englacial  matter  to  become  part  of  the 
subglacial  till,  it  would  account  for  a  part  of  the  glacial  waters  and  for 
the  maintenance  of  the  internal  temperature,  and  it  would  perhaps  help  to 
answer  the  question,  What  effect  did  the  pressure  of  surface  waters,  streams, 
pools,  and  shallow  lakes  have  on  the  development  of  the  subglacial  till 
beneath  them?  For  surface  waters  would  somewhat  help  to  make  the  ice 
more  transparent,  like  a  piece  of  ground  glass  flowed  with  water,  and  we 
know  that  the  larger  superglacial  streams  remove  the  granular  ice  and  reveal 
only  the  clear  solid  ice  in  their  beds.  Such  an  hypothesis,  if  proved,  would 
be  a  welcome  addition  to  our  knowledge  of  glacial  conditions,  if  for  no 
other  reason  than  to  account  for  the  fact  that  the  ice,  after  having  taken 
the  englacial  debris  into  its  grasp  where  it  is  thicker,  lets  go  of  it  again 
subglacially  where  the  ice  is  thinner. 

5.  Subterranean  waters  issuing  as  springs  beneath  the  ice.  The  rocks 
beneath  glaciers  become  charged  with  water,  just  as  they  do  elsewhere,  and 
probably  discharge  it  under  the  ice  in  many  cases.  .Such  waters  would  dis- 
turb the  distribution  of  the  internal  heat  of  the  earth.  In  their  subterra- 
nean courses  they  would  absorb  some  of  the  internal  heat  and  transfer  it  to 
their  place  of  issuance.  If  this  was  beneath  the  ice,  the  heat  would  be 
available  for  melting  or  maintaining  temperature. 


308  GLACIAL  GRAVELS  OF  MAI^^E. 

6.  There  is  another  possible,  though  hardly  probable,  source  of  subgla- 
cial  waters,  which  we  admit  into  our  list  simply  as  a  subject  for  investiga- 
tion. Possibly  it  depends  for  its  basis  wholly  on  our  ignorance  of  the 
structure  of  the  nevti.  It  has  often  been  observed  that  at  the  margin  of 
the  snow  fields  the  solid  ice  extends  under  the  snow.  In  the  Mount  St. 
Elias  reg'ion  Russell  has  seen  it  to  a  depth  of  100  to  200  feet  beneath  the 
snow.  But  the  snow  there  does  not  melt  at  elevations  above  13,000  feet, 
but  comes  down  as  avalanches  upon  the  niyi.  These  conditions  can  not 
be  typical  of  ice-sheets,  for  though  the  latter  may  perhaps  sometimes  rise 
above  surface  melting,  there  are  no  avalanches  to  compact  the  ice,  nor  any 
crevasses  to  admit  water  from  rocks  nearly  bare  of  snow.  Both  Russell 
and  Chamberlin  regard  it  as  probable  that  even  in  such  a  supposed  ice- 
sheet  the  dry  neve  grows  more  compact  as  we  go  downward,  and  finally 
becomes  solid  ice.  A  hole  bored  to  the  bottom  of  the  Greenland  ndve 
would  answer  all  these  questions  of  fact,  but  in  the  absence  of  observations 
it  must  be  considered  as  possible  that  there  are  conditions  under  which  the 
coarse  granular  snow  or  partially  consolidated  ice  extends  beneath  the  zone 
of  surface  melting-,  so  as  to  become  charged  with  seeping  water,  and  near 
enough  to  the  ground  to  permit  its  contained  water  to  escape  to  the  bottom 
of  the  ice  without  the  aid  of  crevasses  as  the  grains  are  slowly  pressed 
together  to  form  consolidated  ice.  This  could  happen  only  under  snow 
fields  unbroken  by  crevasses.  If  this  ever  happens,  the  granular  zone  would 
form  the  fountain  head  of  subglacial  streams. 

BASAL  FURROWS  AS  STREAM  TUNNELS. 

As  the  glacier  flows  over  an  obstruction  a  furrow  is  formed  in  the  base 
of  the  ice.  Though  viscous  to  a  certain  extent  under  ordinary  pressures, 
the  ice  can  not  at  once  fit  itself  to  the  lee  side  of  the  obstruction.  This  is 
proved  not  only  by  the  general  laws  of  the  flow  of  fluids  but  also  by  field 
phenomena,  such  as  the  subglacial  till  that  has  been  seen  to  gather  beneath 
the  ice  of  a  tongue  that  crossed  a  low  part  of  a  hill  in  Greenland,  the 
phenomenon  .of  crag  and  tail,  the  existence  of  hollows  in  the  rock  that 
were  glaciated  not  at  all  or  only  imperfectly,  etc.  The  ice  does  not  always 
change  its  direction  and  bend  downward  when  the  rock  surface  does  so, 
and  thus  small  caves  may  exist  beneath  the  ice.  This  is  proved  by  the 
facts  elsewhere  recorded  as  observed  at  Rockland.     It  is  to  be  noted  that 


BASAL  FURROWS  AS  STREAM  TUNNELS.  309 

tills  liappeued  only  while  the  latest  scratches  were  being  made.  An  earlier 
series  of  scratches  went  up  and  over  and  down  the  slope  of  the  rock  with- 
out distinguishable  break  of  continuity.  These  scratches  do  not  date  from 
the  time  when  ice  was  deepest,  but  are  themselves  deflected  from  the  direc- 
tion of  general  glaciation,  yet  at  the  time  they  were  made  the  ice  could 
flow  down  into  depressions  without  leaving  caves  beneath  it.  The  scratches 
on  the  tops  of  the  highest  hills  date  from  the  time  the  ice  was  deepest,  and 
scratches  parallel  to  this  direction  are  remarkable  for  the  depth  of  the 
depressions  they  go  down  into  and  the  abruptness  of  the  slopes  the}^  are 
able  to  follow.  A  fair  inference  is  that  the  furrows  or  hollows  left  beneath 
the  ice  while  passing  over  uneven  ground,  bowlders,  and  other  obstacles 
are  a  feature  of  thin  glaciers.  Many  observers  have  seen  such  furrows  in 
the  lower  surface  of  the  ice  where  it  flowed  over  bowlders,  but  their  obser- 
vations were  necessarily  made  in  the  crevassed  portions  of  glaciers  near 
the  extremities.  Such  furrows  must  fill  up  by  inward  flow  of  the  ice, 
and  the  rate  Avould  depend  on  pressure,  etc. 

The  hypothesis  that  basal  furrows  and  lee  cavities  have  helped  to  form 
subglacial  stream  tunnels  has  some  quasi  support  from  certain  field  phe- 
nomena. Thus  in  the  coast  region  the  gravels  are  often  found  on  the  tops 
of  low  hills,  but  in  such  places  it  is  probable  that  crevasses  would  be  formed, 
and  these  might  aid  in  the  formation  of  tunnels  far  more  than  the  basal 
cavities.  None  of  the  hillside  eskers  have  been  seen  to  originate  from 
bowlders  or  sharp  peaks  of  rock,  or  to  have  such  in  their  courses.  The 
bosses  of  rock  that  are  sometimes  found  in  the  course  of  an  osar  river  are 
so  low  and  broad  that  only  very  short  cavities  would  form  in  their  lee. 
And  since  such  cavities  were  largest  near  the  extremity  of  the  ice,  where 
crevasses  were  most  numerous  and  sufiiced  to  carry  off  the  waters,  we  must 
infer  that  basal  furrows  and  caves  were  of  little  use  in  establishing  stream 
tunnels. 

Another  conceivable  sort  of  basal  cavity  attracts  attention  as  a  possi- 
bility. Under  unbroken  ice  the  water  of  basal  rhelting  would  be  pressed 
side  wise  from  where  there  is  greater  pressure  to  where  there  is  less  pressure, 
and  collect  beneath  the  ice.  Since  water  is  practically  incompressible,  such 
a  water-filled  cavity  can  not  collapse  in  one  part  without  a  corresponding 
ejtpansion  in  another.  It  would  in  some  respects  be  the  analogue  of  the 
air  bubble  in  water,  though  not  owing  its  shape  to  surface  tension,  and,  like 


310  GLACIAL  GEAVELS  OF  MAINE. 

the  bubble,  could  be  pushed  forward,  to  be  discharged  mto  the  first  crevasse 
or  cavity  formed  in  lee  of  an  obstruction.  By  some  such  process  the  basal 
waters  are  able  to  maintain  a  precarious  and  much-interrupted  passage 
beneath  the  ice. 

At  North  Dixmont  and  elsewhere  osars  that  are  somewhat  transverse 
to  the  glaciation  are  stratified  monoclinally,  the  dip  being  toward  the  lee 
side,  as  if  the  advance  of  the  ice  continually  closed  up  the  stoss  side  of  the 
enlarging  channel  and  left  a  corresponding  opening  on  the  lee  side. 

GENESIS  AND  MAINTENANCE  OF  SUBGLACIAL  AND  ENGLACIAL  CHANNELS. 

Of  this  intricate  subject  our  definite  knowledge  is  phenomenal  and 
general  rather  than  causal  and  detailed.  Rivers  are  known  to  flow  within 
or  beneath  the  ice.  The  surface  waters  plunge  down  crevasses  and  disap- 
pear. These  facts  are  well  known.  But  as  to  the  parts  of  the  work 
wrought  respectively  by  the  ice  and  the  water,  these  and  many  similar 
questions  can  be  argued,  but  not  determined  by  direct  observation. 

No  other  means  than  crevasses  for  the  passage  of  supei-ficial  waters 
beneath  a  sheet  of  ice  covering  all  the  land  has  been  discovered.  If  inter- 
stitial water  reaches  the  ground  through  granular  snow  and  consolidating 
ice,  or  if  surface  pools  melt  their  way  to  the  bottom,  these  processes  would 
hardly  merit  naming-  as  exceptions  to  the  foregoing  rule,  since  they  could 
supply  so  small  an  aniount  of  water.  We  have,  then,  to  consider  the  ice- 
sheet  as  one  of  the  rocks  which  surface  waters  penetrate,  as  they  do  other 
rocks,  along  a  system  of  joints  and  crevices  of  wonderful  complexity  till 
they  reach  the  earth  or  the  bottom  of  the  crevices.  Thus  in  the  first 
instance  the  ice  itself  provides  the  means  for  the  descent  of  the  waters.  It 
is  at  the  escape  of  the  waters  horizontally  that  difficulties  begin.  Gen- 
erally the  streams  are  longitudinal,  while  the  greater  part  of  the  crevasses 
are  transverse.  The  transverse  crevasses  break  up  the  glacier  into  parallel 
blocks  or  pnsmoidal  slices,  each  of  which,  judging  from  surface  appear- 
ances, is  capable  of  acting  as  a  dam  to  hold  back  the  waters  above  it. 
Where  the  ice  is  broken  longitudinally  or,  as  not  infrequently  happens, 
alilie  transversely,  longitudinally,  and  obliquely,  the  waters  find  no  diffi- 
culty in  making  their  way  by  zigzags  through  the  labyrinth  of  crevasses. 
But  it  is  known  that  surface  streams  often  sink  into  the  ice  far  above  the 
oreatly  shattered  j)ortions  of  the  ice-sheet.     There  must  be  subglacial  or 


SUBGLACIAL  AND  ENGLACIAL  CHANlSrELS.  311 

englacial  channels  under  long  reaches  of  ice  unbroken  at  the  surface,  and 
it  is  not  admissible  that  they  were  formed  along  longitudinal  or  any  other 
crevasses.  The  problem  is  solved  so  far  as  the  much-crevassed  ice  is 
concerned.  It  now  remains  to  inquire  how  we  can  account  for  the  exist- 
ence of  longitudinal  channels  within  or  under  parts  of  the  ice  solid  on  the 
surface,  or  if  broken,  not  longitudinally,  but  transversely  into  long  pi-ismoids 
attached  at  the  ends  to  unbroken  ice,  so  that  apparently  they  ought  to  dam 
the  subglacial  waters. 

At  the  outset  we  are  confronted  by  another  quer}^:  How  nearly  do 
the  sui-face  crevasses  represent  those  of  the  bottom  I  Except  at  precipices, 
crevasses  form  at  rig-ht  angles  to  the  tension,  or  nearly  perpendicular  to  the 
ice  surface.  Usually  they  are  not  planes,  but  more  or  less  curved  and 
irregular;  but  even  when  approximately  plane  when  first  made,  they 
become  greatly  distorted  by  the  unequal  flow  of  the  ice.  Also,  since  the 
upper  ice  moves  much  faster  than  the  lower,  the  successive  fractures  divide 
the  ice  into  blocks  that  are  much  wider,  lengthwise  of  the  glacier,  at  the 
top  than  at  the  bottom.  When  the  ice  has  great  depth  and  rapid  motion 
and  crevasses  form  at  short  surface  intervals,  the  bases  of  the  prismoidal 
slabs  must  often  be  narrow,  and  it  may  even  happen  that  the  crevasses 
meet  at  the  ground  or  above  it.  We  must  admit,  therefore,  that  the  basal 
ice  is  broken  by  crevasses  nearer  together  than  at  the  surface,  and  also  that 
by  the  intersection  of  curved  and  irregular  crevasses  it  may  not  seldom 
happen  that  transverse  slabs  of  ice  that  appear  on  the  surface  to  be  capable 
of  acting  as  dams  to  the  subglacial  waters  are  broken  through  in  the 
depths.  After  making  a  most  liberal  allowance  for  cases  where  there  are  no 
apparent  longitudinal  crevasses  but  yet  the  transverse  crevasses  connect,  we 
still  have  a  residue  of  apparently  unbroken  ice  penetrated  by  longitudinal 
subglacial  streams. 

Into  all  crevasses  the  surface  waters  pass.  Part  of  the  crevasses  do 
not  reach  to  the  ground;  part  open  into  subglacial  channels  and  part  do  not. 
Those  crevasses  down  which  the  waters  succeed  in  forcing  a  passage  are 
soon  enlarged  into  the  shaft  or  well  of  a  moulin.  This  enlargement  is 
significant  and  must  be  accounted  for.  At  the  instant  of  melting,  the 
surface  water  has  the  temperature  of  32°,  but  under  sunlight  it  absorbs 
heat  and  rises  in  temperature.  The  water  in  contact  with  the  ice  then  gives 
up  its  surplus  heat  to  melt  a  portion  of  the  adjacent  ice.     This  is  a  slow 


312  GLACIAL  GEAVELS  OF  JNIAIXE. 

process,  since  water  is  a  poor  conductor  of  molecular  lieat,  while  the  absorp- 
tion of  radiant  energy  is  practically  instantaneous.  Volumes  are  as  the 
cubes  of  the  diameters,  and  surfaces  as  the  squares  of  the  diameters;  helice 
the  larger  superficial  streams  contain  a  larger  proportion  of  water  warmed 
above  32°  as  they  pour  into  the  ice.  This  heat  melts  the  ice  of  the 
crevasse  as  it  descends  and  enlarges  the  passage  into  a  shaft,  and  continues 
the  work  after  it  is  beneath  the  ice  in  the  enlargement  of  even  the  narrow- 
est crevasses  into  tunnels.  Water  at  32°  Avould  find  its  way  through  the 
crevasses  as  do  the  subterranean  waters  tlxrough  the  joints  of  the  insoluljle 
rocks,  Avithout  enlarging  the  natural  joints  except  to  a  limited  extent  by 
mechanical  erosion.  Surface  waters  of  the  ice  never  become  heated  very 
much  above  32°,  and  their  melting  power  is  much  more  feeble  than  waters 
warmed  on  the  land. 

Crevasses  not  opening  into  established  subglacial  or  englacial  channels 
may  become  filled  with  water  in  which  convective  currents  soon  begin  to 
carry  heat  to  the  bottom,  since  water  at  39.1°  sinks  and  forces  that  of 
32°  to  rise.  But  crevasses  are  so  deep  in  proportion  to  their  width  that 
only  a  sluggish  circulation  can  be  kept  up  in  them,  and  rarely,  unless 
in  exceptional  cases,  will  stationary  water  be  able  to  melt  for  itself  a  sub- 
glacial  outlet.  The  flow  of  a  surface  stream  over  the  month  of  the  crevasse 
aids  the  melting  by  furnishing  a  constant  supply  of  warmed  water. 

When  a  supei-ficial  stream  pours  down  a  crevasse,  an  enlargement  of 
the  base  of  its  shaft  is  formed,  where  the  water,  falling  at  a  high  velocity 
to  the  ground,  rebounds  outward  in  all  directions.  A  new  crevasse  soon 
opens  at  a  short  distance  above  the  last  one,  and  iu  the  course  of  time  the 
stream  opens  a  new  shaft  in  this  and  abandons  the  old  one.  As  the  ice 
flows  past  the  place  where  the  crevasses  form,  each  part  is  in  succession 
hollowed  out  at  the.  base  of  the  waterfall,  and  thus  a  large  continuous 
tunnel  is  prolonged  by  the  forward  movement  of  the  glacier.  It  is  not 
meant  to  imply  that  the  water  acts  only  at  the  base  of  the  waterfall,  but  it 
acts  there  most  energetically.  Given,  then,  a  waterfall  or  any  other  condi- 
tions whereby  warmed  waters  can  melt  a  passage  underneath  each  suc- 
cessive block  between  the  crevasses,  and  the  glacier  itself  will  prolong  a 
tunnel  distally. 

Let  us  take  the  case  of  a  moulin  supposed  to  be  formed  at  the  proximal 
end  of  a  subglacial  stream — the  successive  transverse  crevasses  not  opening 


SUBGLACIAL  AND  ENGLACIAL  CHANNELS.  313 

into  one  another  but  separated  by  a  solid  slab  of  ice.  When  a  new  cre- 
vasse forms,  it  becomes  filled  with  water,  but  it  is  narrow,  and  melting  by 
convection  currents  is  very  slow.  Under  a  pressure  of  thousands  of  feet  the 
Avater  searches  out  every  point  of  weakness.  It  acts  by  its  pressure  to  rup- 
ture the  ice,  also  to  penetrate  between  the  ice  and  the  underlying  rock,  and 
also  bv  its  superior  weight  to  raise  bodily  the  ice  in  contact  with  it.  The 
last  can  not  be  done  without  fracturing  ice  of  great  thickness,  and  this  the 
flotation  is  not  able  to  do.  The  line  of  contact  between  the  ice  and  the  rock 
is  that  of  weakness,  since  the  adhesion  of  the  ice  and  rock  is  less  than  the 
cohesion  of  the  ice,  and  probably  of  the  ground  moraine,  where  there  is 
one.  If  the  ice  has  been  held  above  the  rock  by  a  film  of  basal  water,  or 
there  is  a  basal  furrow  in  the  bottom  of  the  ice,  the  water  immediately 
penetrates  between  the  ice  and  the  rock,  and  soon  enlarges  the  smallest 
chink  to  the  capacity  of  the  stream.  Moreover,  the  ice  must  flow  down 
into  each  scratch  of  the  rock  or  the  trickle  will  begin  and  all  the  rest 
follow.  Whether  ice  held  under  great  pressure  in  fair  contact  at  all  points 
with  the  rock  could  prevent  the  passage  of  the  waters  is  a  matter  of  con- 
jecture. It  is  possible  that  continued  pressure  might  cause  a  minute  flow 
of  the  ice,  so  as  slowly  to  raise  in  arch  form  the  central  parts  of  the  block 
forming  the  dam,  and  thus  permit  the  water  to  escape.  Only  the  minutest 
opening  would  be  required  to  initiate  the  flow,  and  the  melting  would  do 
the  rest." 

It  is  known  that  ice  can  flow  over  deeply  buried  ridges  without  being 
crevassed  at  the  surface.  If  the  motion  continues  while  the  thickness 
diminishes,  the  time  will  come  when  the  ridge  will  cause  an  increasing 
bulging  of  the  ice  surface,  and  finally  crevasses.  In  many  cases  of  retreat- 
ing glaciers  surface  waters  are  seen  to  pour  down  crevasses  that  would  not 
exist  when  there  was  considerably  deeper  ice,  and  in  these  cases  the  waters 
must  have  established  subglacial  or  englacial  channels  for  themselves  not 
very  long  ago.  At  the  moulin,  where  the  water  in  the  new  crevasse  is 
separated  from  a  large  tunnel  by  at  most  only  a  few  feet  of  ice,  it  is  not  so 
wond-erful  that  it  finds  a  passage.  The  difficulty  is  to  show  how  a  channel 
is  for  the  first  time  established  beneath  Or  within  the  ice,  often  underneath 
lono-  reaches  of  ice  unbroken  at  the  surface.  It  is  constantly  being  done 
on  the  glacier  longitudinally,  yet  the  large  Marjelen  See  can  not  keep  open 
a  permanent  channel  transverse  to  the  ice  flow.     We  seem  to  be  driven  to 


314  GLACIAL  GEAVELS  OF  MAINE. 

the  conclusion  that  the  motion  of  the  ice  not  only  indirectly  establishes  the 
subglacial  drainage  by  furnishing  the  necessary  crevasses,  but  also  directly 
aids  in  the  formation  of  the  channels  in  the  direction  of  motion.  This  it 
does  because  the  modifications  of  the  base  of  the  ice  that  are  made  as  the 
ice  passes  a  given  point  are  carried  forward  by  the  motion.  As  one  of  the 
possible  combinations,  let  us  postulate  a  new  crevasse  appearing  far  from 
any  others,  opening  into  the  basal  cavity  formed  in  the  lee  of  the  obstruc- 
tion causing  the  crevasse,  and  where  no  previous  water  channel  exists. 
When  the  crevasse  fills  with  water,  its  outward  pressure,  owing  to  the 
higher  specific  gravity  of  water,  somewhat  exceeds  the  pressure  due  to 
the  weight  of  the  superincumbent  ice.  The  inward  flow  of  the  ice  to 
fill  the  cavity  in  lee  of  the  obstruction  is  resisted  by  the  viscosity  of  the 
ice  and  the  antagonistic  pressure  of  the  water.  In  the  absence  of  specially 
great  pressure,  such  as  would  be  caused  by  converging  ice  flow  owing  to 
lateral  pressure  of  obstructions,  it  might  happen  that  the  pressure  of  the 
water  filling  the  crevasse  and  basal  cavity  could  resist  the  collapse  of  the 
latter,  or  make  it  very  slow.  If  so,  as  the  lower  ice  moved  forward,  the 
water  would  fill  the  lengthening  furrow  which  would  extend  from  the  base 
of  the  crevasse  backward  to  the  obstruction.  When  a  new  crevasse  was 
formed  at  the  proximal  end  of  the  same  cavity,  the  water  pressure  would 
still  be  maintained,  and  would  continue  while  the  base  of  that  crevasse  was 
in  turn  pushed  forward.  Under  favorable  conditions  the  basal  furrow 
might  thus  be  prevented  from  collapsing  until  its  forward  end  had  been 
brought  to  where  it  opens  into  other  basal  cavities  or  into  a  crevasse.  In 
this  analysis  we  have  avoided  a  comparison  of  the  pressure  exerted  by  the 
inward  flow  with  that  due  to  the  weight  of  the  ice.  Without  insisting  on 
details  where  so  much  remains  unknown,  we  may  in  a  general  way  safely 
affirm  that  the  motion  of  the  ice  greatly  assists  in  the  formation  of  sub- 
glacial  tunnels  in  other  ways  than  simply  by  the  formation  of  crevasses. 
Probably  a  mass  of  motionless  ice  would  have  only  a  surface  drainage. 

How  are  the  channels  of  subglacial  streams  maintained  transversely  to 
the  movement?  Where  transverse  crevasses  form  a  part  of  such  a  channel 
it  is  easy  to  account  for  the  maintenance  of  the  channel.  As  new  crevasses 
opened,  the  stream  would  occupy  them  in  turn  for  a  time,  and  then  abandon 
them,  as  it  did  old  moulin  shafts.  This  implies  that  the  stream  is  pushed 
onward,  whatever  distance  intervenes  between  the  successive  crevasses,  and 


SUBGLAGIAL  AND  ENGLACIAL  CHANNELS.  315 

then  returns  to  its  old  position  in  the  latest  crevasse.  Probably  all  subgla- 
cial  tunnels  wander,  but  the  transverse  ones  more  than  the  longitudinal. 
A  transverse  channel  could  be  stationary  in  two  ways:  by  the  melting  of 
the  ice  as  fast  as  it  advanced,  or  by  becoming  filled  with  sufficient  gravel 
to  force  the  ice  to  flow  over  it.  The  stratified  osars  date  from  a  time  when 
the  channels  were  approximately  stationary,  due  probably  to  both  the  above- 
cited  conditions,  aided  perhaps  by  a  sluggish  ice  movement. 

The  same  causes  Avhich  enlarge  crevices  into  tunnels  maintain  the  tun- 
nels against  a  slow  inward  movement  of  the  ice.  An  instance  is  seen  on 
the  Malespina  glacier,  where  the  subsidence  of  the  roof  of  a  glacier  river 
has  resulted  in  the  formation  of  scarps  of  depression  on  the  upper  surface 
of  the  glacier.  That  glacial  rivers  do  not  succeed  in  eroding  so  broad  can- 
yons and  timnels  in  the  ice  as  they  would  in  rock  is  due  partly  to  the 
gradual  collapse  of  the  walls  and  partly  to  the  fact  that  the  glacier  is  ever 
being  renewed. 

While  we  postulate  some  inward  flow,  the  assumption  must  be  so  held 
as  to  allow  the  formation  of  crevasses,  which  we  can  not  account  for  if  we 
assume  very  much  fluency  or  plasticity. 

In  case  of  a  decaying  ice-sheet  having  its  nc^ve  and  higher  ice  unbroken, 
the  thinning  of  the  ice  over  the  hills  would  from  time  to  time  cause  the 
appearance  of  crevasses  at  places  before  free  from  them.  New  subglacial 
tunnels  would  soon  be  formed,  if  surface  waters  flowed  into  them.  Thus, 
in  Maine,  as  the  ndv^  retreated  northward,  there  would  be  a  corresponding 
advance  of  the  subglacial  rivers,  so  far  as  they  serve  to  carry  off'  superficial 
waters.  The  advance  would  take  place  into  a  region  previously  di-ained  by 
superficial  streams.  The  thinning  of  the  ice  would  cause  a  multitude  of 
crevasses  to  appear  in  new  places,  but  many  of  these  would  be  of  no  sig- 
nificance. To  use  a  biological  phrase,  there  would  be  a  natural  selection 
of  the  crevasses,  only  those  intersecting  the  established  superficial  streams 
having  the  power  to  determine  the  courses  of  the  larger  subglacial  rivers  to 
that  place.  In  this  manner  the  sxipei-ficial  drainage  systems  of  the  ice-sheet 
may  have  had  an  important  influence  in  determining  the  number  and  courses 
of  the  subglacial  rivers. 

It  is  difficult  now  to  ascertain  the  causes  of  the  dividing  of  the  ice- 
sheet  into  superficial  drainage  systems  or  how  far  it  was  determined  by  the 
underlying  hills.     There  may  be  parts  of  the  slush  zone  that  are  so  flat 


316  GLACIAL  GEAVELS  OF  MAINE. 

that  the  courses  of  the  surface  streams  are  detei'mined  by  the  accidents  of 
the  winter  snow  drifts.  Many  observers  report  seeing  domes  and  rounded 
ridges  on  the  ice,  presumably  formed  by  some  buried  obstruction.-^  Instru- 
mental surveys  mig-ht  reveal  shallow  anticlines  or  syiiclines  where  to  the. 
eye  there  was  a  plain.  Where  ice  flows  over  a  ridge  that  is  parallel  to  its 
motion  there  Avill  be  a  bulging  at  the  stoss  end  of  the  ridge,  and  probably 
then  to  leeward  there  would  be  a  shallow  valley  on  the  top  of  the  ridge  for 
a  considerable  distance,  caused  by  the  retardation  of  the  flow  at  the  bulg- 
ing. But  in  Maine  the  hills  were  mostly  transverse,  and  the  transverse 
billows  of  the  ice-sheet  would  be  more  numerous  and  higher  than  the 
longitudinal  ones.  It  is  certain  that  the  osar  rivers  penetrated  the  higher 
hills  by  low  cols  and  passes.  In  many  cases,  especially  in  western  Maine, 
they  must  have  been  subglacial  rivers.  It  is  as  yet  uncertain  whether  we 
are  to  attribute  the  courses  of  these  subglacial  rivers  wholly  to  conditions 
existing  within  or  beneath  the  ice,  or  whether  we  can  trace  additional  links 
in  the  chain  of  causation  and  can  declare  that  the  courses  of  the  subglacial 
were  in  part  determined  by  those  of  the  superficial  streams,  and  that  these 
in  turn  were  determined  to  the  low  passes  by  the  undulations  of  the  surface 
ice  as  it  flowed  over  the  adjacent  hills.  Such  an  investigation  could  not 
proceed  far  without  the  aid  of  a  topographical  map.  The  facts  in  the  field 
certainh^  seem  in  numerous  cases  to  favor  the  hypothesis.  The  topic  will 
be  referred  to  later. 

FORMS    OF    GLACIAL    CHANNELS. 

Observation  proves  that  the  subglacial  and  many  of  the  englacial 
channels  have  arched  roofs.  This  is  chiefly  due  to  the  fact  that  the  waters 
are  always  in  contact  with  the  lateral  walls,  but  only  in  time  of  flood  can 
they  reach  to  the  roofs  to  melt  them,  and  partly  because  water  of  39.1°  tends 
to  sink  to  the  bottom.  In  case  of  a  roaring  stream  this  would  have  little 
effect,  but  it  might  be  an  important  element  in  case  of  a  quieter  flow,  as 
when  a  stream  enters  an  eidargement  of  its  channel  or  goes  up  and  over  a 
hill.     That  the  melting  is  most  rapid  near  the  bottom  of  a  cavity  that  con- 

'  Lieuteuaiit  Peary,  Bull.  Am.  Geog.  Soc,  vol.  19,  p. 287,  1887,  says:  "As  to  the  features  of  the 
interior  beyond  the  coast-liue,  the  surface  of  the  'iee  hlink'near  the  margin  is  a  succession  of 
rounded  hummocks,  steepest  aud  highest  on  their  landward  sides,  Tphich  are  sometimes  precipitous. 
Farther  in,  these  hummocUs  merge  into  long  iiat  swells,  which  in  turn  decrease  in  height  toward  the 
interior,  until  at  last  a  flat,  gently  rising  plain  is  reached,  which  doubtless  becomes  ultimately  level." 

See  also  Prof.  I.  C.liussell,  Nat.  Geog.  Mag.,  vol.  3,  pp.  106, 107, 132,  May  29,  1891. 


ENLAEGEMENTS  OF  GLACIAL  CHANNELS.  317 

tains  water  warmed  above  32°  is  proved  by  the  overhang  at  the  margin  of 
glacial  lakes  and  by  the  enlargement  at  the  bottoms  of  glacial  pools  and 
lakelets.  On  Hagues  Peak,  Colorado,  is  an  ice  field  that  is  shding,  if  not 
flowing,  and  the  walls  of  the  subglacial  outlet  of  a  small  lake  overhang  at 
an  angle  of  45°  or  more  in  a  curve  convex  downward. 

In  case  of  superficial  and  englacial  channels  the  bottom  as  well  as  the 
sides  is  more  or  less  melted  and  eroded  by  the  glacial  waters ;  hence  the 
base  does  not  enlarge  laterally  so  much  as  when  the  bed  is  composed  of 
rock,  and  such  streams  gen- 
erally form  more  canyon- 
like channels.  But  if  they 
succeed  in  melting  their  beds 

down  to  the  ground  the  chan-      rro,  25.— Ideal  sections  across  channels  of  superficial  glacial  streams. 

«,  before  reaching  the  base;  &,  after  reaching  the  base. 

nels  then  begin  to  enlarge 

at  the  tase,  and  the  walls  to  overhang,  like  those  of  a  subglacial  stream. 
Gravel  deposited  in  such  a  channel  would  be  a  ridge  with  arched  cross 
section,  like  that  found  in  a  subglacial  tunnel. 

The  accompanying  cut  (fig.  25)  was  drawn  in  1888,  and  can  be  com- 
pared by  the  critical  reader  witli  the  more  recently  published  photographs 
of  the  Malespina  glacier  by  Russell. 

EXTRAORDINARY  ENLARGEMENTS  OF   THE  GLACIAL  RIVER  CHANNELS. 

When  we  follow  one  of  the  ordinary  osars  for  50  miles,  we  become 
greatly  impressed  by  the  narrowness  and  steepness  of  the  ridge.  Some 
of  the  hillside  and  smaller  osars  are,  toward  tlieir  northern  ends,  only  5  to 
15  feet  wide  at  the  base.  Their  material  here  is  very  little  worn  and 
rounded,  and  the  streams  that  deposited  them  were  brooks.  The  height  of 
the  osar  proper  usually  exceeds  one-eighth,  and  sometimes  locally  reaches 
to  one-fom^th  or  one-third,  of  its  base.  That  rivers  capable  of  transporting 
so  great  a  quantity  of  sediment  should  occupy  so  narrow  channels  is  truly 
wonderful  when  we  consider  the  softness  of  ice  as  compared  with  the 
hardness  of  the  debris  transported  and  its  consequent  liability  to  mechan- 
ical erosion,  also  that  it  was  liable  to  melting,  a  process  which  has  its 
analogue  in  the  action  of  subterranean  waters  or  calcareous  rocks,  and 
might  be  expected  to  result  in  the  formation  of  subglacial  and  englacial 
channels  comparable  to  the  great  limestone  caves.  That  the  glacial  rivers 
do  not  ordinarily  succeed  in  doing  this  is  due,  I  conceive,  chiefly  to  the 


318  GLACIAL  GEAVELS  OF  MAINE. 

constant  renewal  of  the  living  glacier.  Canyons  cut  in  rock  exhibit  the  cumu- 
lative effects  of  erosion  on  a  fixed  bed.  But  the  ice-sheet  of  to-day  is  not 
that  of  the  last  century.  Pressing  onward  from  age  to  age,  just  as  new  gener- 
ations of  men  rise  to  do  the  world's  work,  the  worn,  rounded,  and  wasted 
glacier  loses  itself  at  the  glance  of  the  sun,  before  its  streams  have  time  to 
enlarge  their  channels  very  greatly,  and  is  replaced  by  a  new  and  unbroken, 
youthful  glacier,  eager  to  run  its  race.  The  slow  inward  flow  of  the  ice 
also  assists  in  preventing  enlargement  of  the  channels  of  the  streams. 

In  addition  to  the  small  narrow  ridges  we  find  others  broadening  to  an 
eighth  of  a  mile  or  more,  with  corresponding  height,  or  expanding'  into 
massive  ridges  or  mounds  one-half  to  three-fourths  of  a  mile  in  breadth 
and  a  mile  or  more  in  length,  with  a  height  of  100  to  150  feet.  We  find 
hundreds  of  miles  of  osar  terraces  one-eighth  to  one-half  a  mile  in  breadth, 
level  in  cross  section  or  with  a  central  ridge  rising  above  the  rest  of  the 
plain,  going  up  and  over  hills  or  skirting  hillsides  as  terraces  in  a  way 
to  prove  they  were  at  the  time  of  deposition  confined  on  one  or  both  sides 
by  ice.  We  find  cones,  domes,  mounds,  and  ridges  of  very  small  as  well 
as  large  size,  but  all  in  situations  such  that  they  must  have  been  deposited 
in  channels  or  basins  in  the  ice.  We  find  osar  border  clay  deposited  in  the 
broadened  channel  of  an  osar  river,  which  is  in  some  cases  probably  marine — 
i.  e.,  an  osar  channel  became  a  fiord  in  the  ice.  We  find  channels  of  the 
ice  one-fourth  mile  to  a  mile  wide  filled  with  deltas  which  at  their  distal 
ends  are  marine.  From  a  diminutive  osar  like  one  of  the  ridges  near 
SoiTth  Acton  or  the  little  gravel  hummocks  near  the  Head  of  the  Tide, 
Belfast,  up  to  the  Whalesback,  Aurora,  or  the  so-called  "mountains"  of 
Greenbush,  or  the  broad  osar  terraces  of  York  and  Oxford  counties,  the 
distance  is  immense.  Before  the  final  disappearance  of  the  ice-sheet  it 
Avas  gashed  and  pierced  and  sliced  by  a  complex  system  of  channels,  most 
of  the  time  of  large  size  and  irregular  shapes.  Is  this  self-destructive!  If 
so,  it  is  no  more  suicidal  than  the  behavior  of  a  glacier  could  be  expected 
to  be  that  was  forced  to  supply  water  for  its  own  destruction.  The  drainage 
waters  of  ordinary  Aljjine  glaciers  immediately  escajie,  but  this  ice-sheet 
went  over  many  transverse  hills,  and  to  the  north  of  the  hills  there  were 
large  permanent  bodies  of  water  which  toward  the  last  were  eating  out  its 
vitals.  To  complete  its  misfortunes  the  sea  rose,  and  by  the  greater  sub- 
sidence to  the  northwest  it  found  itself  on  a  bed  sloping  against  it  over 


DIRECTIONS  OF  GLACIAL  RIVERS.  319 

large  areas.  In  the  time  of  its  strength  the  ice-sheet  could  so  far  strangle 
its  rivers  that  only  a  little  sediment  was  left  in  their  channels,  but  the 
sediment  was  poured  out  in  front  of  the  ice  where  the  sea  now  is.  But  in 
its  decay,  when  the  flow  became  sluggish  and  even  the  ground  turned 
against  it  and  increasing  quantities  of  solar  heat  were  transmitted  through 
the  ice,  the  gravel  was  left  far  back  of  the  ice  front.  In  the  Rocky 
Mountains  substantially  all  the  glacial  gravels  were  frontal  or  overwash 
plains,  and  the  same  was  true  of  large  portions  of  the  northwestern  Interior. 
In  Maine  the  marine  deltas  and  a  large  part  of  the  reticulated  kames  were 
deposited  in  front  of  the  ice,  also  much  of  the  valley  drift;  but  in  addition 
to  these  there  is  a  very  great  development  of  gravels  that  were  deposited 
within  the  area  then  covered  by  the  ice.  For  the  great  enlargement  of  the 
glacial  stream  channels  we  need  invoke  only  the  same  causes  that  first 
estabhshed  them  as  tunnels.  Mechanical  erosion,  melting  by  warmed 
waters,  and  heat  transmitted  through  the  ice,  are  sufficient  to  do  the  work 
when  acting  through  thin  ice  whose  motion  was  sluggish  or  in  places 
almost  arrested,  aided  by  the  rising  sea,  the  bodies  of  water  lying  to  the 
north  of  the  hills,  the  increasing .  quantities  of  water  warmed  under  the 
sunlight  either  by  the  melting  of  the  roofs  of  their  tunnels  or  their  being 
forced  up  onto  the  ice  by  the  clogging  of  their  channels,  etc.  Toward  the 
last  probably  most  of  the  water  in  the  channels  of  the  broad  osars  or  osar 
terraces  was  exposed  to  the  sunlight.  If  the  narrowness  of  the  earl}-  osars 
is  remarkable,  the  broadness  of  the  later  ones  is  equally  remarkable. 

These  extraordinary  enlargements  of  the  stream  channels  were  made 
in  the  last  days  of  the  ice  at  the  place  of  enlargement,  all  the  other  condi- 
tions being  favorable.  Mechanical  erosion  was  active,  but  still  more  effect- 
ive was  that  insinuating,  ever  alert  agent,  heat,  whose  transformations  within 
the  decaying  ice-sheet  were  varied  and  powerful. 

DIRECTIONS   OF   GLACIAL    RIVERS    COMPARED  WITH    THE    FLOW  OF   THE    ICE. 

Our  definite  knowledge  of  the  courses  of  the  rivers  of  the  ice-sheet  is 
derived  from  the  sediments  they  have  left  behind  them  and  the  excavations 
they  made  in  the  till  and  the  solid  rock.  When  we  map  the  gravels,  we 
map  only  those  portions  of  their  channels  in  which  sediment  was  deposited. 
In  large  portions  of  their  courses  the  flow  must  have  been  too  swift  to  per- 
mit the  deposition  of  sediment.     While  it  is  impossible  now  to  reconstruct 


320  GLACIAL  GEAVELS  OF  MAINE. 

the  map  of  all  the  streams  of  the  4ce-sheet,  enough  is  known  to  enable  ns 
to  mark  out  the  courses  of  the  larger  rivers.  In  some  cases  the  gravel  is 
residual  rather  than  transported — that  is,  the  streams  had  barely  power  to 
cany  off  the  finer  matter  of  the  till,  leaving  the  larger  fragments  with  but 
little,  if  any,  water  transportation  from  tiie  place  where  the  ice  brought 
them.  In  a  multitude  of  cases  no  doubt  small  trickles  and  brooklets  car- 
ried off  some  of  the  finer  matter  of  the  till,  leaving  it  a  little  more  sandy 
than  the  iisual  till,  but  s,uch  we  can  hardly  trace.  In  a  number  of  places 
glacial  streams  formed  potholes,  but  have  left  no  gravels.  In  places 
we  find  the  ground  moraine  eroded  and  glacial  gravel  left  at  some  point 
southward. 

Although  the  general  or  average  directions  of  the  rivers  were  roughly 
parallel  to  the  direction  of  ice  flow,  there  are  many  important  divergences. 
Most  of  the  shorter  meanderings  are  plainly  transverse  to  the  scratches  on 
the  rocks,  and  so  are  some  of  the  larger  zigzags  of  5  to  30  miles.  The  maps 
show  that  a  number  of  the  osar  rivers  had  tributary  branches  like  those  of 
ordinary  rivers,  and  at  their  places  of  junction  I  have  found  no  proof  from 
the  scratches  that  there  was  a  similar  convergence  of  the  ice  movements. 
In  like  manner,  where  the  delta  branches  diverge,  there  is  no  corresponding 
divergence  of  the  scratches.  They  diverge  or  converge  at  large  angles  up 
to  a  right  angle,  and  it  is  difficult  to  conceive  causes  for  such  ice  move- 
ments. It  is  true  that  the  latest  ice  movements  were  recorded  by  shallow 
scratches  on  rocks  bare  of  ground  moraine,  and  from  which  the  glaciated 
surface  has  now  generally  weathered,  aided  by  forest  fires  or  by  those  made 
in  clearing  the  land.  But  after  making  the  largest  admissible  allowance 
for  the  imperfections  of  the  record  it  is  still  diflicult  to  assign  causes  for 
such  a  converging  flow  as  must  have  taken  place  near  the  head  of  Penobscot 
Bay  (the  reader  is  referred  to  the  map,  PL  XXXI,  for  explanation),  or  in 
Grreenbush,  or  near  Tomah  station  of  the  Maine  Central  Railroad.  As 
elsewhere  noted,  there  is  a  convergence  of  glacial  rivers  toward  Columbia 
and  Jonesport.  The  scratches  also  converge  toward  the  same  region,  but 
not  so  nmch  as  the  rivers.  The  Coast  Survey  charts  give  the  soundings  for 
a  few  miles  off  the  coast,  and  I  fail  to  find  any  deep  valley  in  the  sea  floor, 
or  other  topographical  reason  for  such  a  converging  flow  of  the  ice;  and 
there  is  just  as  little  topographical  reason  for  the  flow  of  the  rivers  for  30 
miles   of-  more    transversely  to  the  ice    movement,  as  testified   both  by 


TOPOGRAPHICAL  RELATIONS  OF  GLACIAL  RIVEPvS.  321 

scratches  and  bowlder  trains.  I  see  no  admissible  interpretation  but  this: 
Osars  for  long  distances  are  transverse  to  the  recorded  glacial  movements, 
and  probably  even  the  latest  ice  movements  were  not  parallel  with  them. 
In  the  coast  region,  as  near  Belfast,  there  are  usually  one  or  more  systems 
of  glacial  scratches  that  diverge  progressively  more  and  more  from  those 
that  mark  the  time  of  deepest  ice,  the  latter  being  parallel  to  the  scratches 
found  on  the  tops  of  the  highest  hills.  Here  we  find  the  systems  of  dis- 
continuous gravels  approximately  parallel  to  the  scratches  last  made,  and 
convergent  like  them,  to  Belfast  Bay. 

The  great  divergence  of  the  glacial  rivers,  both  for  short  and  long 
distances,  from  the  recorded  movements  of  the  ice  suggest  many  questions 
as  to  the  causes  that  determined  the  courses  of  the  rivers.  The  subject  is 
briefly  treated  in  the  following-  chapter. 

RELATIONS  OF  GLACIAL  RIVERS  TO  RELIEF  FORMS  OF  THE  LAND. 

The  general  facts  as  to  the  topographical  relations  of  the  osar  rivers 
have  already  been  stated.  These  rivers  often  flowed  over  the  lower  hills, 
but  not  over  hills  higher  than  200  feet  except  in  western  Maine,  where  many 
gravel  series  go  over  hills  a  little  more  than  200  feet,  and  over  one  hill  400 
feet,  above  the  ground  on  the  north. 

A  question  o'f  detail  arises  whether  the  glacial  streams  were  determined 
to  the  low  passes  before  the  hills  adjoining  the  passes  emerged  from  the 
ice,  premising  that  it  is  only  rarely  in  Maine  that  ridges  are  parallel  with 
the  direction  of  ice  movement.     Almost  alwaj'-s  they  are  transvei'se. 

The  phenomena  of  delta  branches  proves  that  a  single  glacial  river 
sometimes  either  used  too  widely  diverging  channels  simultaneously  or 
abandoned  one  of  the  channels  for  another.  This  phenomenon  is  very  com- 
mon in  southwestern  Maine  and  over  most  of  the  State.  But  these  delta 
branches  go  over  no  higher  hills  than  the  tributary  branches  or  main  osars, 
and  they  throw  no  light  on  the  time  the  glacial  rivers  were  established  in 
the  low  passes. 

The  hills  adjoining  the  low  passes  penetrated  by  the  glacial  rivers  rise 
to  a  height  of  100  to  1,000  or  more  feet  above  the  passes.  If  at  or  near 
the  time  that  the  ice  melted  over  the  transverse  hills  bordering  the  passes, 
glacial  streams  crossed  them,  we  ought  under  certain  conditions  to  find 
traces  of  such  streams. 

MON  XXXIV 21 


322  GLACIAL  GRAVELS  OF  MAINE. 

1.  If  subglacial,  they  ought  to  have  left  channels  of  erosion  in  the  till 
or  deposits  of  glacial  gravel,  at  least  on  the  south  sides  of  the  hills,  like  the 
hillside  eskers. 

2.  If  superficial,  there  would  come  a  time  ^Yhen  the  top  of  the  thmmng 
ice  did  not  rise  so  far  above  the  hills  but  that  the  channels  would  cut  down 
through  the  ice  to  the  till.  Erosion  of  the  till  would  follow  until  the  hill 
emerged  from  the  ice.  The  eroded  matter  would  be  left  somewhere  as 
glacial  gravel.  Or  if  the  surface  streams  disappeared  down  crevasses  at  the 
tops  of  the  hills,  they  ought,  while  escaping  as  subglacial  streams,  to  erode 
the  till  and  leave  gravels. 

3.  The  lowering  of  the  ice  to  the  top  of  a  hill  would  necessaril}" 
deflect  to  some  neighboring  pass  any  stream  previously  crossing  the  hill. 
The  deflection  might  take  place  in  various  ways.  It  might  happen  some 
miles  to  the  north,  or  a  pool  might  be  formed  on  the  north  slope  of  the  hill 
which  would  in  fact  so  far  check  the  force  of  the  stream  that  it  would 
deposit  only  scanty  sediments  that  might  since  have  been  wholly  or  partly 
eroded.  But  we  can  at  least  conceive  of  a  stream  thus  deflected  leaving 
gravel  terraces  to  mark  its  new  channel  along  the  northern  slope  of  the  hill 
or  at  some  point  north.  One  such  case  would  be  very  significant.  As 
elsewhere  recorded,  there  are  cases  on  the  north  sides  of  hills  of  lateral 
deflection  from  the  general  course  of  large  glacial  rivers,  as  at  South  Albion 
and  in  Montville  and  elsewhere,  but  no  gravels  on  the  hills  marking  more 
ancient  channels  than  those  in  which  the  osars  proper  were  deposited. 

The  Grreenland  and  Alaskan  glaciers  show  prominent  bulging  on  their 
surface,  presumably  due  to  passing  over  hidden  hills.  Such  bulgings  must 
appear  while  the  tops  of  the  obstacles  are  a  considerable  distance  beneath 
the  ice.  Whenever  bulging  of  the  surface  is  accompanied  by  deep  crevasses 
it  would  be  possible  for  surface  streams  here  to  escape  beneath  the  ice  as 
subglacial  streams,  but  it  must  often  have  happened  that  the  raising  of  the 
ice  over  the  hills  would  cause  the  surface  water  to  gather  in  the  lower  parts 
of  the  ice  surface,  i.  e.,  over  the  low  passes  of  the  underlying  hills.  How 
far  such  bulging  over  transverse  hills  helped  establish  the  courses  of  the 
rivers  through  the  passes  is  uncertain. 

Numbers  of  the  hillside  kames  are  situated  on  the  south  slopes  of  hills 
higher  than  200  feet  above  the  ground  on  the  north.  The  small  size  of  the 
gravel  deposits  does  not  call  for  large  streams  or  long-continued  flow.     In 


SEDIMENTATION.  323 

some  cases  it  appears  probable  that  the  local  drainage  of  the  hillside  would 
furnish  all  the  water  required  to  deposit  the  gravel.  But  there  are  other 
cases  (as  that  found  near  Wilton,  elsewhere  described)  where  the  stream  was 
of  good  size  at  the  top  of  the  hill.  In  such  cases  the  streams  must  have 
had  a  gathering  ground  to  the  north.  Of  course  such  streams  ceased  to  flow 
when  the  hills  rose  to  the  surface  of  the  ice,  but  thus  far  I  have  found  no 
traces  of  deflection  channels  into  which  they  turned  after  their  original 
channel  was  interrupted. 

Summary. — Some  of  tho  streams  that  deposited  the  hillside  kames  appear 
to  be  instances  of  glacial  streams  whose  career  was  cut  short  by  the  lower- 
ing of  the  ice  to  the  tops  of  transverse  hills.  Thus  far  I  can  not  identify 
them  with  any  of  the  long  rivers,  nor  trace  any  channels  they  abandoned 
for  others.  In  the  case  of  delta  branches  the  glacial  rivers  maj^  have 
abandoned  one  channel  for  another,  but  such  branches  obey  the  same  law 
respecting  low  passes  as  the  main  rivers.  In  case  of  the  larger  rivers  pene- 
trating low  passes,  there  is  as  yet  no  field  proof  that  the  rivers  even  flowed 
anywhere  except  where  the  osars  were  deposited.  The  general  inference 
follows  that  the  courses  of  the  great  glacial  rivers  were  determined  to  the 
low  passes  before  the  osars  were  deposited  or  the  adjoining  hills  were  bare 
of  ice. 

SEDIMENTATION    IN    PLACES    FAVORABLE    OR    UNFAVORABLE    TO    THE 
FORMATION   OF   CREVASSES. 

The  discontinuous  gravel  deposits  found  near  the  coast  region  often 
form  on  a  lenticular  hill  or  drumlin,  as  near  Belfast,  or  on  the  tops  of  low 
hills,  as  near  Portland.  Both  the  Kennebec  and  the  Penobscot  rivers  for 
many  miles  are  flanked  by  osars,  somewhat  discontinuous,  that  are  for  the 
most  of  the  distance  found  at  the  flanks  of  the  valleys  or  near  the  top  of 
the  steep  bank  50  to  100  feet  above  the  rivers,  just  where  crevasses  would 
naturally  form.  Near  Lewiston  the  Androscoggin  River  shows  the  same 
peculiarity  for  a  few  miles. 

On  the  other  hand,  some  of  the  discontinuous  gravels  are  in  the  bot- 
toms of  valleys  or  on  level  ground  where  there  appears  to  be  no  inequality 
of  the  ground  to  cause  crevasses.  So,  also,  the  long  osars  love  to  zigzag 
over  broad  plains,  often  through  swamps,  where  the  land  is  very  level  and 
even  and  there  is  no  apparent  cause  for  crevasses.     They  often  follow  the 


324  GLACIAL  GRAVELS  OF  MAINE. 

axis  of  a  valley  or  zigzag-  from  one  side  to  the  other  in  a  way  that  shows  no 
connection  with  the  inequalities  of  the  land. 

Thus  far  I  have  been  able  to  make  no  generalization,  but  certainly  the 
determination  of  the  positions  of  the  crevasses  is  a  difficult  matter,  and  per- 
haps often  impossible.  Many  details  in  regard  to  particular  places  will  be 
found  in  the  descriptions  of  the  gravel  systems. 

GLACIAL    RIVERS    OF    MAINE;    SUMMARY. 

In  the  preceding  pages  we  have  spoken  of  the  great  leng'th  and  volume 
of  the  glacial  rivers  of  Maine  as  attested  by  the  gravels  they  deposited. 
Care  has  been  taken  to  avoid  naming  them  either  subglacial  or  superficial. 
From  whatever  point  of  view  we  look,  the  difficulties  are  immense  in 
accounting  for  the  branchings  of  the  rivers  of  the  ice-sheet,  their  directions 
and  their  relations  to  the  relief  forms  of  the  land,  the  nature  of  their  sedi- 
ments, etc.,  on  the  theory  that  we  are  dealing-  with  subglacial  streams  alone. 
To  insist  that  the  glacial  gravels  are  wholly  due  to  subglacial  streams,  or 
wholly  to  superficial  streams,  appears  to  me  to  be  dangerously  like  the  dis- 
pute between  the  followers  of  Hutton  and  those  of  Werner  as  to  whether 
the  earth  had  come  to  its  present  condition  by  the  action  of  water  or  fire. 
Both  sides  of  that  controversy  were  partly  right  and  partly  wrong,  and 
probably  this  is  the  case  in  the  controversy  as  to  the  glacial  streams. 
Those  who  study  the  question  near  the  great  terminal  moraines  will  every- 
where see  signs  of  subglacial  streams  only.  Those  who  study  in  north- 
ern New  England  will  also  see  phenomena  that  are  consistent  with  the 
hypothesis  of  superficial  streams.  It  is  too  early  for  anyone  to  settle  finally 
the  moot  question  of  glacial  streams.  In  the  following  interpretations  I 
have  endeavored  to  correlate  the  facts  in  Maine,  so  far  as  I  have  observed 
them,  with  those  of  Greenland.     The  best  interpretation  will  prevail. 

GLACIAL    POTHOLES. 

The  process  of  pothole  making  has  long-  been  well  understood  in  the 
form  in  which  it  appears  in  the  beds  of  surface  streams  of  the  land.  If  we 
go  to  some  place  where  a  rapid  stream  passes  over  a  series  of  waterfalls 
and  rapids,  especially  over  granite  rocks,  we  can  see  potholes  in  all  stages 
of  formation      An  accessible  locality  is  the  falls  of  the  Androscoggin  River 


GLACIAL  POTHOLES.  325 

at  Brunswick.  Here  and  there  the  water  can  he  seen  flowing  over  an 
angular  depression  in  the  rock,  where  a  portion  of  tlie  granite  has  broken 
away  under  the  action  of  frost,  ice  gorges,  the  force  of  the  water,  etc.  In 
process  of  time  the  surface  is  sand  carved  and  liollowed  out  into  bowl 
shape.  The  water  falls  into  the  cavity,  rebounds  in  a  curve,  and  swiftly 
shoots  up  the  other  side.  Up  to  this  time  the  sand  grains  and  stones  of 
various  sizes  used  by  the  stream  in  this  process  are  driven  almost  imme- 
diately out  of  the  cavity,  along  with  the  upward  rebound  of  the  water. 
By  degrees  the  ca^^ty  deepens,  until  some  day  a  stone  falls  into  the  bowl 
of  such  size  that  the  water  can  not  roll  it  up  the  steepened  slopes.  '  The 
stream  now  sets  this  stone  to  rolling,  at  first  with  considerable  vertical 
motion,  but  more  and  more,  as  the  hole  deepens,  the  horizontal  whirling 
prevails.     The  grinding  now  proceeds  with  multiplied  rapidity. 

The  conditions  for  the  formation  of  a  pothole  are  the  following:  (1)  A 
rapid  stream.  (2)  A  rock  firm  enough  to  withstand  the  direct  impact  of 
the  water.  Thus  potholes  are  more  frequently  found  in  granites,  sand- 
stones, and  indurated  slates  than  in  schists  and  shales  easily  weathered  or 
split  and  broken  under  the  action  of  the  water.  (3)  The  formation  of  such 
a  cavity  as  to  permit  a  vortical  motion  of  the  water.  (4)  A  moderate 
quantity  of  stones  for  the  stream  to  whirl  around  in  the  hole.  If  there  is 
a  large  quantity  of  sediment  swept  along  by  the  stream,  the  cavity  will 
soon  be  filled  or  partly  filled  with  stones  and  the  process  of  excavation 
will  be  stopped.     Sooner  or  later  most  potholes  are  filled  in  this  way. 

It  is  important  to  note  that  the  direct  impact  of  the  running  water  bears 
a  very  subordinate  part  in  pothole  erosion.  The  principal  agency  is  the 
friction  of  the  rolled  stones  and  bowlders.  It  makes  little  diff"erence  whether 
the  water  falls  into  the  cavity  from  above  or  is  shot  horizontally,  or  nearly 
so,  across  the  mouth  of  the  opening,  provided  the  water  is  kept  whirling. 
The  best-laaown  glacial  potholes  in  Maine .  are  situated  near  Riggs 
Landing,  on  the  island  of  Georgetown.  They  were  examined  and  measured 
by  me  in  1879.  The  region  has  since  been  explored  by  Mr.  P.  C.  Manning, 
of  Portland,  whose  observations  were  presented  hi  a  paper  read  before 
the  Portland  Society  of  Natural  History.  He  found  similar  potholes  in 
several  other  of  the  islands  situated  east  and  southeast  of  Bath.  Some 
of  these  were  called  to  his  attention  by  Mr.  Alexander  Johnston,  of  Wis- 
casset.     Several  times  archeologists  have  asserted  that  these  potholes  were 


326  GLACIAL  GRAVELS  OF  MAINE. 

excavated  by  the  Indians.  That  tliey  are  gdacial  potholes  is  proved  by  the 
following  facts: 

One  of  the  potholes  near  Rig-gsville  is  situated  about  Ih  miles  south- 
ward from  that  place,  on  the  shore  of  Robin  Hoods  Cove.  The  pothole  is 
covered  by  about  1  foot  of  water  at  time  of  ordinary  liigh  tide.  It  is  near 
10  feet  in  depth;  its  average  diameter  is  4  feet  at  the  tojj  and  6  feet  at  the 
bottom.  It  is  excavated  in  a  little  shelf  of  rock  on  the  side  of  a  rather  steep 
ledgy  hill,  about  40  feet  hig'h.  Within  a  few  rods  this  hill  slopes  in  the 
opposite  direction  from  the  shore,  down  to  the  valley  of  a  small  brook 
which  enters  the  cove  about  one-eighth  of  a  mile  north  of  the  pothole.. 
The  ground  slopes  down  from  the  hill  in  all  directions,  so  that  the  only  sur- 
face drainage  that  eA^er  could  reach  this  pothole  must  have  come  from  a 
slope  only  a  few  rods  long.  The  rock  is  a  compact  gneiss,  with  no  veins 
or  dikes  at  this  place  and  no  fault  or  fracture.  I  could  find  no  other  sign 
of  running  water  in  the  vicinity.  There  were  stones  in  the  bottom  of  the 
hole  that  could  be  moved  around  by  an  oar,  but  I  had  no  means  of  getting 
them  out,  and  it  was  impossible  to  see  more  than  2  feet  into  the  black  water. 
Robin  Hoods  Cove  is  here  near  one-fourth  of  a  mile  wide,  and  contains  no 
islands  or  rocks  to  cause  a  tidal  race.  About  one-eighth  of  a  mile  north  of 
Riggs  Landing  are  two  potholes  at  an  elevation  of  about  60  feet  above  the 
sea.  The  one  situated  at  the  southwest  is  about  4  feet  in  diameter  and  5 
feet  deep.  The  other  is  about  6  feet  in  diameter  and  10  feet  deep.  Both 
are  nearly  round,  and  the  walls  are  quite  smooth.  The  layers  of  gneiss, 
tilted  np  at  high  angle,  are  continuous,  except  where  interrupted  by  the 
holes.  The  same  laj^ers  can  be  readily  traced  on  opposite  sides  of  the  holes. 
There  is  no  sign  of  veins  or  fractures.  In  the  potholes  were  rounded  peb- 
bles and  bowlders,  one  of  them  3  feet  in  diameter,  well  rounded  at  the 
edges  and  angles.  Some  of  the  rounded  stones  had  been  taken  out  by 
previous  explorers.  The  lioles  are  situated  on  the  southern  slope  of  a  hill 
of  gneiss  that  rises  150  feet  (by  aneroid)  above  the  sea.  The  hillside  shows 
much  bare  rock  and  is  broken  by  numerous  hillocks  and  small  valleys.  We 
reach  the  top  within  about  one-fourth  of  a  mile  from  the  shore.  All  the 
surface  drainage  that  ever  could  have  reached  the  holes  came  from  this  hill- 
side, and  that,  too,  on  an  irregular  surface  where  no  single  valley  exists  to 
direct  the  flow  of  water  to  these  holes. 

About  one-half  mile  north  of  Riggs  Landing  there  is  a  pothole  on  the 


GLACIAL  POTHOLES,  327 

shore  situated  a  foot  or  two  above  high  tide.  It  is  2  feet  in  diameter  and 
4  feet  deep.  About  4  feet  west  of  this  hole  is  a  shallow  bowl  with  very 
smooth  inner  surface,  an  incipient  pothole.  There  are  several  masses  of 
water-rounded  gravel  near  here,  which  at  the  time  of  my  visit  I  supposed 
to  be  esker  gravel,  probably  deposited  by  the  same  glacial  stream  that 
formed  the  potholes.  I  am  now  uncertain  whether  it  is  esker  or  beach 
gravel. 

No  one  familiar  with  potholes  could  fail  to  recognize  as  potholes  these 
round  wells  with  smoothly  polished  inner  surface,  even  if  he  did  not  find 
within  some  of  them  the  round  cobbles  and  smoothed  bowlders  used  in 
grinding  out  the  cavity.  All  are  found  on  short  slopes.  There  is  hardly  a 
grass  field  in  Maine  that  would  not  contain  potholes  if  these  were  produced 
by  land  waters.  The  potholes  are  manifestly  in  places  where  no  ordinary 
streams  can  ever  have  flowed,  and  miTst  be  due  to  the  action  of  glacial 
streams.  These  potholes  are  found  in  a  region  where  there  is  a  larger 
propoi'tion  of  bare  rock  than  in  any  other  part  of  the  Maine  coast.  They 
are  sitviated  a  few  miles  east  of  the  Kennebec  River.  At  the  time  the  sea 
stood  at  the  225-230-foot  level  the  whole  region  was  deeply  under  water 
and  exposed  to  the  force  of  the  Atlantic.  The  rocks  are  gneissoid  and 
schistose,  which  rocks  usually  produced  more  till  than  is  seen  in  this  region. 
The  scarcity  of  till  is  in  part  due  to  marine  erosion  and  in  part  to  the  sub- 
glacial  streams.  If  other  regions  were  as  bare  of  till  as  this,  it  is  possible 
we  might  find  glacial  potholes  everywhere  along  the  coast.  It  is  incredi- 
ble that  Indians  excavated  holes  such  as  these. 

In  the  interior  of  the  State  the  only  potholes  known  to  me  are  found 
in  the  beds  of  streams,  with  a  single  exception.  This  is  situated  in  the 
town  of  Paris,  abovit  one-half  mile  west  of  Snows  Falls.  It  was  first 
pointed  out  to  me  by  Mr.  N.  H.  Perry,  mineralogist,  of  South  Paris.  By 
aneroid  it  is  240  feet  above  Snows  Falls.  Above  these  falls  the  valley  of 
the  Little  Androscoggin  widens  into  a  triangular  basin  3  miles  in  diameter. 
The  pothole  is  situated  near  the  top  of  a  hill  lying  directly  south  of  this 
broad  open  valley,  and  if  the  valley  were  filled  by  a  glacier  the  ice  would 
naturally  abut  against  this  hill.  From  the  highest  point  of  the  hill  (about 
300  feet  above  the  river)  a  ridge  extends  northeastward  down  the  slope. 
At  one  place  this  ridge  is  cut  aci'oss  at  right  angles  by  a  ravine  100  feet 
wide,  bordered  on  each  side  by  steep  rocks  rising  about  20  feet.     On  the 


328  GLACIAL  GEAVELS  OF  MAINE. 

northeast  side  of  the  ravine  there  is  a  narrow  step  or  shelf  situated  about 
halfway  between  the  top  and  the  bottom  of  the  wall.  Its  position  is  shown 
in  the  accompanying  diagram.  The  hole  is  nearly  round.  It  is  21  inches 
in  diameter,  16  inches  deep  on  the  lower  side,  and  2  feet  on  the  upper. 
The  iipper  part  of  the  interior  is  somewhat  weathered  and  rough.  The 
lower  part,  which  is  generally  filled  with  water,  is  very  smoothly  polished. 
The  bottom  is  almost  hemispherical.  The  granite  of  the  region  weathers 
rough.  These  facts  prove  it  to  be  a  pothole,  not  a  freak  of  weathering. 
Its  situation  halfway  up  the  side  of  a  cliff  and  within  a  few  rods  of  the 
highest  part  of  the  ridge,  whence  the  water  flows  in  several  different  direc- 
tions, conclusively  proves  that  it  can  not  have  been  formed  by  an}'  stream 
of  surface  drainage.  A  glacier  moving  from  the  north  would  naturally  be 
broken  by  crevasses  as  it  flowed  over  the  cliff.  This  would  be  a  favorable 
place  for  a  stream  flowing  on  the  surface  of  the  ice  to  plunge 
to  the  bottom  and  escape  as  a  subglacial  stream.  I  could 
find  no  glacial  g-ravel  in  the  vicinity.  A  subglacial  stream 
flowing  from  this  point  southward  would  fall  more  than  200 
feet  within  a  mile,  and  might  be  expected  to  sweep  its  chan- 
nel clear  of  sediment.     If  a  subglacial  stream  from  the  north 

Fig.  26.— Section    of  i.«>   • 

cliff  and  pothole;  flowcd  up  the  loug  hill  aud  over  the  clifi  it  probably  ought 
to  have  left  sediment  or  other  sign  on  an  up  slope  that  rises 
at  least  200  feet  within  a  mile.  The  north  slope  of  the  hill  is  covei-ed 
deeply  with  the  ordinary  granitic  till  of  the  region,  without  glacial  gravel 
or  erosion  channel  or  any  other  sign  of  a  glacial  stream.  The  only  admis- 
sible interpretation  of  these  facts  that  occurs  to  me  is  that  a  superficial 
stream  here  tumbled  down  a  crevasse  that  formed  as  the  ice  passed  up 
the  clifis. 

Can  potholes  be  formed  at  the  foot  of  a  moulin  shaft?  Professor  Dana 
has  suggested  that  the  change  in  position  of  the  waterfall  due  to  the 
advance  of  the  ice  would  produce  an  elongated  rather  than  a  round  cavity. 

It  is  a  fact  that  as  each  crevasse  moves  onward  a  new  crevasse  is  pro- 
duced in  the  rear  of  the  former,  and  a  new  well  is  soon  excavated  down 
the  crevasse  last  formed.  It  will  naturally  result  that  the  water  will  not 
continually  fall  in  the  same  place,  but  over  an  area  as  long  as  the  distance 
between  the  successive  shafts.  In  other  words,  each  shaft  beg'ins  at  a  cer- 
tain place  and  moves  on,  suljjecting  all  the  rock  over  which  it  passes  to  the 


GLACIAL  POTHOLES.  329 

direct  impact  of  the  water,  until  it  is  superseded  by  the  next  crevasse, 
which  then  repeats  the  process.  But  there  must  be  an  enlargement  at  the 
base  of  the  shaft,  A-arying-  in  size  according  to  the  size  of  the  stream,  the  depth 
of  ice,  and  the  amount  of  warmed  water.  This  may  in  many  cases  permit 
the  water  to  scatter,  so  that  it  will  not  strike  the  rock  in  a  round  definite 
stream.  But  be  this  as  it  may,  the  direct  mechanical  impact  of  the  water 
against  the  rock  has  very  little  to  do  with  eroding  potholes  except  to  start 
the  process  It  is  chiefly  the  stones  rolled  round  and  round  by  the  water 
that  do  the  work.  Were  the  rock  so  soft  that  mechanical  erosion  by  the 
water  exceeded  the  attrition  of  the  whirling  stones,  we  should  have,  not  a 
smooth-walled  pothole,  but  a  canj^on  of  erosion  with  irregular  surface. 
When  once  a  cavity  is  found  or  made  which  is  deep  enough  to  prevent  the 
stones  swept  along  by  the  stream  from  being  prematurely  washed  away, 
the  erosion  hj  the  rolling  stones  would,  in  case  of  hard  rocks,  so  far  exceed ' 
the  mechanical  erosion  of  the  water  that  the  shape  of  the  well  would  be 
that  due  to  the  attrition  of  the  stones,  with  hardly  a  trace  of  direct  water 
erosion.  All  that  is  needed  is  that  the  water  in  the  pothole  be  kept  whirl- 
ing. When  a  nearly  vertical  cascade  strikes  the  rock,  the  water  must  shoot 
swiftly  outward  on  all  sides  in  nearly  a  horizontal  plane.  If  a  pothole 
were  within  reach  of  these  out-rushing  waters,  the  water  within  it  would  be 
kept  whirling  as  well  as  if  a  vei'tical  stream  fell  into  it.  Whether,  then,  the 
water  at  a  glacier  mill  falls  directly  into  a  pothole  or  anywhere  near  it,  it 
will  continue  to  whirl  the  water  in  the  hole.  And  the  hole  would  be  as 
round  as  one  formed  by  any  other  stream,  unless  the  nature  of  the  rock 
permitted  it  to  be  easily  eroded  by  the  direct  impact  of  the  water. 
Regarding  glacial  potholes,  my  conclusions  are  as  follows: 

1.  They  may  be  formed  by  subglacial  streams. 

2.  They  may  be  formed  at  the  foot  of  the  waterfall  wliere  a  superficial 
stream  jiours  down  a  crevasse. 

3.  They  form  only  where  the  stream  carries  but  little  sediment  or  is 
swift  enough  to  keep  its  channel  clear  of  sediment,  or  nearly  so.  If  a  stream 
begins  to  drop  its  sediment  an  incipient  pothole  would  soon  fill  up  and 
ultimately  would  be  covered  by  a  mass  of  glacial  gravel. 

4.  The  velocity  of  subglacial  streams  is  so  great,  since  they  are  urged 
by  a  great  pressure  from  behind,  that  they  might  be  able  to  form  potholes 
at  a  considerable  depth  beneath  the  sea  or  a  lake  into  which  they  might 


330  GLACIAL  GRAVELS  OF  MAINE. 

flow.  A  superficial  stream  falling  down  a  crevasse  could  also  whirl  the 
water  at  a  considerable  depth,  if  it  was  of  large  size.  The  glacial  water- 
falls are  often  many  hundred  feet  high,  and  the  water  attains  a  high  velocity 
in  falling.  How  deep  beneath  the  water  potholes  could  thus  be  formed  is 
uncertain.  In  any  particular  case  we  should,  in  order  even  to  guess,  have 
to  know  the  size  of  the  streams  and  the  thickness  of  ice. 

5.  The  existence  of  glacial  potholes  in  places  remote  from  any  recog- 
nizable glacial  gravels  is  proof  that  not  every  glacial  stream  left  sediments. 
Only  the  larger  masses  of  the  drift  of  these  streams  have  thus  far  been 
mapped.  The  smaller  masses  are  buried  beneath  the  englacial  (upper)  till 
or  the  marine  clays  of  the  coast  region.  So  also  are  the  potholes  and  ero- 
sion channels  excavated  by  the  subglacial  rivers  in  the  solid  rock.  I  have 
not  found  any  of  the  latter  in  Maine  which  are  of  geological  importance, 
but  Professor  Dana  showed  me  one  of  this  kind  near  New  Haven. 

FORMATION   OF   KAMES   AND   OSARS. 

Ridges,  domes,  and  plains  rising  50  to  150  feet  above  the  surrounding 
till  testify  that  a  very  large  amount  of  work  has  been  expended  in  bringing 
so  great  masses  together.  They  usually  rise  to  a  greater  height  and  show 
gTeater  thickness  than  equal  areas  of  till  in  the  same  regions.  On  the 
average  they  are  areas  of  unusual  accumulation.  They  can  not  have  been 
derived  from  the  local  subglacial  till  supplemented  by  the  englacial  till 
Contained  in  a  body  of  ice  of  such  length  and  breadth  as  at  the  given  place 
deposited  an  area  of  till  equal  to  that  covered  by  the  gravel.  A  supply  must 
have  been  brought  from  abroad.  And  since  a  large  amount  of  the  finer 
detritus  of  the  till  is  washed  away  in  the  process  of  making  glacial  gravel, 
this  foreign  supply  must  have  been  large.  Such  local  accumulations  might 
be  caused  in  variotis  ways. 

1.  In  case  of  the  longer  glacial  rivers,  flowing  as  they  did  up  and  over 
hills,  we  might  expect  areas  of  till  erosion  on  steep  down  slopes  or  near  the 
tops  of  passes,  where  the  swift  streams  carried  all  before  them,  alternating 
with  areas  of  accuiuulation.  In  places  all  the  till,  both  subglacial  and 
englacial,  has  disappeared,  and  often  all  but  the  coarsest  of  the  water-rolled 
matter.  In  other  places  (as  at  The  Notch,  Garland),  the  osar  river  did  not 
succeed  in  eroding  all  the  till  over  which  it  flowed.  This  erosion  of  the  till 
in  the  course  of  osar  rivers  sometimes  took  place  along  a  definite  channel 


FORMATION  OF  KAMES  AND  OSAES.  331 

of  erosion  bordered  by  rather  steep  walls  (as  north  of  Hogback  Mountain, 
Montville),  but  more  often  the  erosion  is  diffused.  We  see  that  till  is  absent, 
but  we  find  no  bank  or  margin  which  can  be  said  to  mark  the  limit  reached 
by  erosion.  A  characteristic  form  is  shown  in  PI.  XXVI,  A.  .  The  discon- 
tinuous osars  lie  in  regions  so  covered  by  marine  clays  that  we  do  not  know 
Avhat  forms  the  erosion  takes. 

2.  It  is  evident  that  during  the  last  days  of  the  ice-sheet  the  englacial 
morainal  matter  would  appear  on  the  surface  in  consequence  of  the  melting 
of  the  ice  above  it.  There  would  form  on  the  ice  a  multitude  of  small 
superficial  streams  and  seeps  which  would  carry  off  much  of  the  finer  part 
of  the  exposed  till  and  precipitate  it  into  the  main  channels.  The  larger  of 
these  lateral  tributaries  formed  the  short  tributaries  of  the  osar  rivers  else- 

■  where  recorded.  No  matter  whether  the  longer  ridges  were  deposited  by 
subglacial  or  superglacial  streams,  in  either  case  there  must  have  been  a 
midtitude  of  superficial  tribiitaries  that  have  left  little  or  no  gravel.  Indeed, 
their  work  was  almost  wholly  erosive,  not  constructive.  Their  slopes  were 
probably  steep.  They  simply  carried  away  such  of  the  till  of  the  region 
they  drained  as  they  could  lift,  and  cast  it  into  the  main  river  channels, 
where  it  either  went  to  make  up  the  osar-ridges  or  was  carried  into  lakes  or 
the  sea  to  form  a  part  of  the  glacial  deltas.  The  larger  stones  over  which 
these  brooks  flowed  would  be  left  in  place  and  be  but  little  polished.  Being 
in  the  tapper  part  of  the  till  the  signs  of  water  wash  and  wear  would  in 
most  cases  long  since  have  disappeared  by  weathering.  The  diffused  ero- 
sion of  the  englacial  till  could  be  accounted  for  by  the  action  of  a  multi- 
tude of  these  lateral  streams.  A  diffused  erosion  of  the  subglacial  till  is 
more  difficult  to  explain,  unless  by  the  wandering  of  the  streams. 

3.  The  flow  of  the  ice  no  doubt  often  helped  to  bring  osar  matter 
together. 

(a)  At  the  end  or  front  of  moving  ice.  In  this  case  the  flow  of  the 
ice  constantly  brings  moraine  matter  to  the  front  and  throws  it  down  for 
the  subglacial  streams  to  act  upon  as  they  swiftly  emerge  from  their 
tunnels.  In  such  a  case  the  sediments  deposited  in  front  of  the  ice 
would  consist  partly  of  worn  matter  transported  from  a  distance  by  the 
subglacial  streams  (or  superficial,  if  such  there  should  be),  and  partly  of 
matter  which  would  othei'wise  form  part  of  the  amorphous  terminal 
morame  and  which  happened  to  be  dropped  into  the  streams  very  near 


332  GLACIAL  GRAVELS  OF  MAINE. 

the  end  of  the  ice.  Such  matter  would  be  less  rolled.  Where  the  ice 
met  the  sea  a  marine  delta  would  be  formed  in  front  of  it.  Where  the 
ice  front  was  above  the  sea,  as  was  probably  the  case  for  a  time  in  the 
valleys  of  the  Carrabassett  and  several  other  streams  at  about  the  same 
distance  from  the  coast,  plains  of  gravel  were  formed  in  the  valleys  in 
front  of  the  ice.  With  respect  to  the  glacial  streams  and  the  ice  front,  these 
may  be  termed  frontal  deltas  or  overwash  aprons.  They  are  the  correlatiA^e 
of  the  sediments  formed  in  front  of  all  glaciers  ending  on  the  land.  Such 
a  series  of  frontal  plains  were  found  south  of  the  g'reat  terminal  moraines 
of  the  ice-sheet  for  a  considerable  part  of  their  length.  At  the  south  end 
of  Sebago  Lake  a  very  deep  mass  of  glacial  gravel  accumulated,  and,  as 
elsewhere  explained,  ice  movements  probably  contributed  to  bring  this 
great  mass  together,  although  it  must  be  admitted  that  glacial  streams  can 
transport  sediments  long  distances. 

(h)  When  the  flow  of  a  subglacial  stream  was  transverse  to  that  of 
the  ice.  The  great  size  of  the  stones  and  bowlders  contained  in  the  gravels 
of  the  hilly  country  west  of  the  Saco  River,  and  other  facts,  favor  the 
hypothesis  that  they  were  deposited  in  large  part  by  subg'lacial  streams. 
If  so,  the  eskers  must  often  have  been  deposited  in  such  subglacial 
channels  transversely  to  the  flow  of  ice,  for  the  ridges  of  those  reticulated 
series  of  kames  trend  in  every  direction.  In  this  case  either  (1)  the  ice 
pushed  the  channel  with  its  contained  sediments  bodily  forward,  or  (2)  the 
ice  flowed  over  the  gravel,  or  (3)  the  ice  was  melted  and  eroded  by  the 
stream  as  fast  as  it  advanced,  or  (4)  the  ice  may  sometimes  have  been 
stationary.  The  truth  probably  combines  the  second  and  third  hypotheses, 
and  in  both  cases  some,  morainal  matter  would  be  dropped  into  the  channel 
as  the  ice  passed  over  it. 

(c)  When  the  channel  was  parallel  with  the  direction  of  ice  flow.  In 
this  case  it  is  certain  that  there  would,  especially  in  case  of  deep  ice,  be 
more  or  less  flow  of  the  ice  inward  from  the  sides.  That  the  channel  did 
not  then  collapse,  like  an  unused  moulin  shaft,  must  be  due  to  the  antago- 
nistic action  of  the  stream  enlarging  its  channel.  Some  till  would  be  con- 
tained within  the  ice  melted  and  eroded  as  it  flowed  inward,  and  thus  some 
esker  matter  would  be  brought  together. 

(d)  In  most  glf^ciers  the  swiftest  flow  is  found  near  the  glacial  river. 
This  must  in  part  be  due  to  the  fact  tliat  the  ice  is  there  generally  the 


A.      BARE    LEDGES    IN    CHANNEL   OF   GLACIAL   RIVER;    PARSONSFl  ELD.      LOOKING   SOUTHEAST, 
Most  of  the  bowlders  in  sight  have  been  water-rolled. 


-^^. 


S.     OSAR  SPRINKLED    WITH    TILL   BOWLDERS;    PROSPECT, 
Flanks  of  ridge  partly  covered  with  marine  clay ;    bowlders  attnbuted  to  floes  of  sea  ic 


BOWLDERS  OF  THE  GLACIAL  GRAVELS.  333 

thickest;  yet  it  is  also  possible  that  the  presence  of  abundant  subglacial 
waters  facilitates  the  flow  of  ice  in  some  degree.  Both  causes  would  pro- 
duce an  obhque  flow  inward  toward  the  hue  of  swiftest  motion.  Such  a 
movement  would  bring  till  matter  to  the  stream,  or  nearer  to  it. 

So  far  as  movements  of  the  ice  brought  the  matter  of  the  kames  and 
osars  together,  they  distinctly  resemble  the  medial,  lateral,  or  terminal 
moraines  of  ordinary  valley  glaciers.  Converging  glacial  striae  are  else- 
where recorded. 

BOWLDERS  OF  THE  GLACIAL  GRAVELS. 

When  bowlders  are  found  on  the  surface  of  masses  of  glacial  sedi- 
ments, it  is  important  to  determine  whether  they  have  been  worn  and  pol- 
ished by  water  action.  This  often  requires  considerable  excavation,  since 
it  is  only  beneath  the  earth,  where  it  has  been  protected  from  the  action  of 
the  weather,  that  we  can  expect  the  pohshed  surface  to  have  been  preserved. 
Many  bowlders  of  coarse  granite  have  so  far  weathered  and  fallen  to  pieces 
since  the  glacial  epoch  that  even  beneath  the  ground  it  is  now  impossible 
to  know  with  certainty  whether  they  Avere  once  polished  or  not.  Omitting, 
then,  some  undetermined  cases,  the  bowlders  of  the  glacial  sediments  may 
be  classed  as  follows: 

1.  Below  the  highest  level  of  the  sea  are  many  bowlders  not  smoothed 
by  running  water  which  overlie  both  the  fossiliferous  marine  clays  and  the 
coarser  glacial  sediments,  also  the  osar  border  clays.  They  have  the  shapes 
and  rough  surfaces  characteristic  of  bowlders  of  the  upper  (englacial)  till. 
They  are  scattered  here  and  there  at  intervals,  generally  one  in  a  place,  but 
sometimes,  especially  on  the  north  sides  of  hills,  in  heaps  and  sheets.  They 
are  most  abundant  on  slopes  favorable  to  the  grounding  of  floes  of  shore  ice. 
The  deposits  are  so  discontinuous  and  helter-skelter  in  their  distribution  and 
so  unlike  a  sheet  of  till  in  composition  and  structure  that  I  attribute  them 
to  floes  of  shore  ice  or  small  bergs.  Two  theories  suggest  themselves: 
that  there  was  a  readvance  of  the  ice  over  the  marine  clays,  the  ice  con- 
taining but  little  drift,  or  that  the  bowlders  tumbled  down  from  the  ice  upon 
clays  formed  in  front  of  the  ice  during  its  retreat  before  the  sea. 

2.  Bowlders  are  sometimes  found  in  the  till  beneath  the  glacial  gravel 
and  projecting  upward  into  the  gravel.  In  some  cases  the  parts  projecting 
above  the  till  were  distinctly  water-polished.  This  is  a  very  common 
occui-rence  at  the  marine  glacial  deltas. 


334  GLACIAL  GRAVELS  OF  MAINE. 

Instances  are  elsewhere  recorded  (see  p.  161)  where  streams  and 
springs  have  eroded  portions  of  the  glacial  marine  deltas  and  exposed  till 
strewn  with  bowlders  just  like  the  ordinary  till  of  the  locality,  or  where 
the  delta  is  thin  the  tops  of  the  larger  bowlders  project  above  the  gravel. 

3.  Bowlders  having  rounded  and  polished  surfaces  are  found  within  or 
partly  within  the  glacial  gravels.  These  must  be  as  truly  a  part  of  the 
formation  as  the  finer  sediments.  There  are  multitudes  of  them  in  the 
gravels  of  southwesterm  Maine  of  all  sizes  up  to  6  feet  in  diameter. 

4.  Elsewhere  are  described  certain  large  bowlders  found  in  the  northern 
part  of  Baldwin.  They  are  situated  on  a  northern  slope  in  the  midst  of 
medium  sand,  and  have  little  or  no  water  pohsh.  The  sand  is  hoiizontally 
terraced  in  such  a  way  as  to  suggest  that  the  bowlders  were  deposited  by 
floating  ice  in  a  broad  osar  channel  which  contained  a  lake-like  body  of  water 
confined  between  the  ice  on  the  north,  east,  and  west  and  the  hill  situated  to 
the  south.  An  alternative  hypothesis  i's  that  the  broad  osar  channels  were 
overarched  by  ice  resting  upon  the  water  that  collected  north  of  the  hills. 

5.  In  the  case  of  the  larger  ice  channels,  especially  the  superficial 
ones,  floating  ice  would  often  transport  stones  and  bowlders  hke  any  other 
river  ice.  I  do  not  know  how  in  all  cases  to  distinguish  whether  a  bowlder 
not  polished  and  rounded  was  dropped  from  the  ice  into  the  bed  of  the 
glacial  river,  or  was  transported  by  floating  ice,  or  was  driven  along  by  ice 
gorges.  We  know  that  ice  dams  to-day  are  efficient  means  of  transporting 
large  bowlders.  Not  many  years  ago  in  Rowland  an  ice  gorge  of  the 
Piscataquis  River  forced  upward  a  very  large  bowlder  10  feet  out  of  the 
bed  of  the  river  and  left  it  on  the  silty  flood  plain  several  rods  back  from 
the  channel  of  the  river.  The  ice  gorges  of  the  osar  channels  must  have 
been  efficient  means  of  transporting  bowlders  and  leaving  them  in  the 
midst  of  fine  sediment. 

6.  Bowlders  not  water-polished  are  found  here  and  there  on  the  surface 
of  the  osar  border  clay,  i.  e.,  the  clay  deposited  in  a  very  much  broadened 
osar  channel.  These  broad  channels  were  from  one-eighth  to  near  three- 
fourths  of  a  mile  wide,  and  it  is  extremely  improbable  that  they  were 
subglacial.  The  few  stones  and  bowlders  they  here  and  there  contain  were 
almost  certainly  dropped  by  floating  ice.  If  arched  by  ice  for  so  great  a 
width,  it  was  probably  sustained  by  flotation  on  the  underlying  water. 

7.  There  are  considerable  numbers  of  bowlders  not  waterworn,  which 


BOWLDERS  OF  THE  GLACIAL  GKAYELS.  335 

quite  certainly  slid  down  into  the  channel  of  the  glacial  river  from  the  ice 
overhead  or  the  walls  at  the  sides.  Such  are  the  bowlders  overlying  the 
osar  at  the  south  end  of  the  Grand  Lake  of  the  St.  Croix.  (See  p.  75.) 
In  the  wilderness  a  few  miles  southeast  of  Aurora  the  gravel  of  the  great 
Katahdin  osar  is  found  in  an  interesting  relation  to  a  train  of  granite 
bowlders.  The  place  is  situated  in  the  valley  of  Leighton  Brook,  a  tribu- 
tary of  the  Middle  Branch  of  the  Union  River.  The  course  of  the  train 
is  nearly  north  and  south,  and  parallel  with  the  ice  flow.  The  train  con- 
sists of  bowlders  piled  one  above  another  so  as  to  make  a  moraine-like 
ridge  10  to  30  feet  high,  and  some  of  the  bowlders  are  10  to  20  feet  in 
diameter.  The  osar  here  forms  a  broad  ridge  of  sand,  gravel,  and  cobbles 
transverse  to  the  bowlder  train.  The  train  comes  up  to  the  edge  of  the 
osar,  and  several  of  its  bowlders  overlie  the  gravel.  Near  the  same  place 
the  osar  crosses  another  similar  ridge  of  till,  and  its  flanks  are  overlain  by 
the  bowlders. 

An  important  and  difficult  question  arises  concerning  the  proper  inter- 
pretation of  the  facts  as  to  the  presence  of  large  water-rolled  bowlders  as 
an  integral  part  of  the  kame  or  osar  gravel.     Several  facts  should  be  noted. 

1.  In  many  places,  especially  in  western  Maine,  the  large  bowlders  are 
more  abundant  in  the  kames  and  osars  than  in  the  same  amount  of  the 
-average  till  of  the  region.  (See  PI.  XXVII,  A.)  This  is  due  to  the  finer 
part  of  the  till  having  been  washed  away,  leaving  the  coarser  residue. 

2.  Almost  universally  the  largest  bowlders  of  the  till  are  most  abun- 
dant at  the  surface.  In  the  glacial  gravels  the  larger  bowlders  are  as 
often,  perhaps  more  often,  contained  in  the  lower  part  of  the  gravel.  The 
two  an-angements  so  alternate  in  the  glacial  gravels  as  to  make  the  inter- 
pretation doubtful.  Most  of  the  large  bowlders  in  the  glacial  gravel  are 
found  in  the  granite  areas,  sometimes  underlying  and  sometimes  overlying 
finer  sediments. 

In  this  connection  we  must  also  consider  what  has  become  of  the 
bowlders  that  were  contained  in  the  ice  that  was  melted  and  eroded  during 
the  formation  and  maintenance  of  the  channel  in  which  the  glacial  sediment 
was  deposited.  This  ice  must  have  contained  its  average  proportion  of 
bowlders,  yet  over  large  areas  only  fine  matter  appears  on  the  surface  of 
the  osars  and  osar-plains.  As  elsewhere  noted,  we  have  reason  to  believe 
that  the  osars  are,  on  the  average,  areas  of  accumulation.     With  material 


336  GLACIAL  GliAVELS  OF  MAmE. 

that  may  De  termed  indigenous — because,  in  order  to  become  a  part  of 
the  glacial  gravel,  it  only  needed  to  be  laid  bare  by  the  melting  and 
erosion  of  the  ice  around  it — there  is  mixed  much  matter  derived  from  the 
subglacial  till  or  the  adjacent  regions.  The  indigenous  matter,  as  it  was 
released  from  the  ice,  necessarily  fell  into  the  channel  and  became  mixed 
with  the  foreign  drift.  The  details  of  osar  transportation  are  very  complex, 
and  the  interiDretation  in  case  of  individual  bowlders  is  doubtful,  in  view  of 
the  many  alternative  fates  that  might  happen  to  any  particular  stone  or 
bowlder.  When  a  polished  bowlder  overlies  finer  sediment,  we  know  the 
order  of  deposition,  but  we  do  not  know  whether  the  bowlder  fell  from  the 
roof  of  an  ice  vault,  or  slid  down  from  the  overhanging  walls  of  a  canyon, 
or  was  transported  to  the  place  by  moving  water,  or  by  floating  ice,  or  by 
an  ice  gorge.  Unfortunately  the  pi'esence  of  large  water-rolled  bowlders 
does  not  give  us  a  conclusive  answer  to  the  question  whether  they  were 
transported  by  subglacial  or  superficial  streams.  Yet  where  they  overlie 
finer  sediments,  the  larger  the  number  of  such  bowlders  the  greater  is  the 
probability  that  they  were  dropped  from  the  roof  of  a  subglacial  vault. 
This  is  a  sufficient  dynamical  cause  for  large  bowlders  being  lifted  above 
finer  sediments,  and  it  is  a  constant  and  inevitable  feature  of  the  marginal 
part  of  an  ice-sheet.  Certainly  a  less  number  of  bowlders  will  be  con- 
tained in  the  ice  of  the  overhanging  walls  of  an  open  channel  than  in  the 
whole  roof  of  an  arch.  Besides,  the  other  modes  of  transportation  named 
are  agencies  that  would  naturally  be  occasional  rather  than  constant  methods 
of  the  glacial  river. 

Summary. — In  casc  of  a  Superficial  river,  the  melting  and  erosion  of  the 
ice  in  the  channel  would  proceed  from  above  downward  to  the  ground,  and 
then  laterally  outward.  The  disposition  of  the  larger  bowlders  of  the  till 
indicates  that,  on  the  average,  the  large  bowlders  were  as  high  in  the  ice 
as  the  finer  materials  were,  or  probably  higher  than  they  were.  If  so, 
these  large  bowlders  would  first  be  laid  bare  in  the  bottom  of  the  deepen- 
ing superfcial  channel.  Subsequently  deposited  sediments  would  be  laid 
on  top  of  them  or  at  their  sides.  The  only  large  bowlders  di'opped  from 
the  ice  into  the  osar  channel  would  be  from  the  overhanging  lateral  walls. 
We  thus  see  that  in  case  of  a  sujDei-ficial  canyon  most  of  the  bowlders  of 
the  upper  till  contained  within  the  ice  melted  or  eroded  to  form  the  chan- 
nel ought  to  be  beneath  the  gravel.     The  argument  is  complicated  by  the 


RETICULATED    RIDGES   OF   COARSE   WATER-ROLLED    GRAVEL;    PARSONSFI  ELD.      LOOKING    NORTH. 
Glacial  river  flowed  through  low  pass  in  distance  down  the  hill  to  the  foreground. 


B.     STRATIFICATION    OF  GLACIAL   MARINE   DELTA;    MONROE. 


BOWLDEliS  OF  GLAOIAL  GKAVELS.  337 

fact  that  we  have  no  proof  that  the  whole  length  of  an  open  canyon  would 
be  simultaneously  an  area  of  deposition.  On  the  contrary,  the  analogies 
all  favor  the  hypothesis  that  as  the  ice  retreated  northward  the  more  north- 
ern portion  of  superficial  channels  would  be  areas  of  denudation,  their 
drift  being  swept  southward  and  deposited  nearer  the  margin  of  the  ice- 
sheet.  If  so,  we  would  have  at  each  place  the  ice  all  melted  in  the  bottoms 
of  the  channels  before  sediments  began  to  be  deposited,  and  this  would 
result  in  all  the  bowlders  first  being  freed  from  ice  and  left  on  the  bed  of 
the  canyon,  to  be  afterwards  covered  with  finer  drift.  This  would  well 
account  for  the  long  reaches  of  osars  and  osar-plains  containing  few  or  no 
large  bowlders  on  the  surface. 

In  case  of  a  subglacial  river,  the  enlargement  proceeded  from  below 
upward  and  laterally.  The  bowlders  contained  in  the  ice  forming  the  roof 
of  the  vault  would  from  time  to  time  drop  into  the  channel  as  it  became 
enlarged  and  they  were  released  from  the  ice.  If  the  bowldei-s  were  high 
up  in  the  ice,  they  would  be  last  to  fall.  Yet  if  at  this  place  the  velocity 
were  such  as  to  sweep  all  the  finer  matter  from  the  channel,  these  bowlders 
might  be  left  on  the  bed  of  the  subglacial  stream.  Then  as  the  ice  became 
thinner  a  time  might  come  when  fine  matter  would  be  deposited  at  this 
place,  and  now  be  found  overlying  the  large  bowlders.  So  also  the  local 
land  slopes  must  be  considered,  i.  e.,  whether  the  place  of  observation  was 
on  up  or  down  slopes. 

Thus  the  large  bowlders  do  not  form  a  crucial  test  between  the  sub- 
glacial and  superglacial  streams.  Yet  we  are  warranted  in  affirming  that 
the  presence  of  very  large  quantities  of  fine  sedimentary  matter  overlying 
the  till  bowlders  is  consistent  with  the  hypothesis  of  a  superficial  stream, 
and  the  presence  of  a  large  number  of  rolled  bowlders  in  the  upper  parts 
of  the  glacial  gravels  can  be  considered  as  probable  evidence  of  a  subglacial 
stream.  The  fewer  the  number  of  such  bowlders  in  the  one  case  and  the 
greater  the  number  in.  the  other,  the  greater  becomes  the  degree  of  proba- 
bility. And  the  matter  is  still  further  complicated  by  the  great  difference 
in  the  size  of  the  bowlders  furnished  by  the  different  kinds  of  rock.  In 
slate  regions  there  might  be  found  only  one  bowlder  to  a  square  rod,  while 
in  granite  regions  there  might  be  ten  or  twenty.  A  superficial  channel 
would  show  very  different  deposits  in  the  two  cases,  yet  they  would  be 
formed  in  the  same  manner;  and  so  of  a  subglacial  stream. 

MON  XXXIV 22 


B38  GLACIAL  GEAVELS  OF  MAINE. 

REMARKS  ON  THE  GEACIATION  OF  THE  ROCKY  MOUNTAINS. 

The  g-laciatiou  of  the  Rocky  Mountains  throws  some  light  on  the 
glaciation  of  Maine,  and  therefore  a  few  of  the  principal  valleys  are  here 
briefly  described.  Questions  j^ertaining  to  the  problems  of  two  or  more 
glaciations  of  the  mountains  and  the  water  drift  of  Tertiary  time  are 
omitted  as  not  having  a  direct  bearing  on  the  questions  arising  in  Maine. 

LA  PLATA  MOUNTAINS. 

These  mountains  are  situated  in  southwestern  Colorado  (no:-th  latitude 
37°  25'),  and  rise  above  13,000  feet.  They  lie  to  the  west  of  the  San  Juan 
Mountains,  and  are  the  first  high  mountains  encountered  by  the  warm 
southwest  winds  that  bring  moisture  from  the  Pacific  Ocean.  To  the  west 
and  southwest  lies  the  great  plain  of  Arizona  and  southern  Utah,  out  of 
which  rise  here  and  there  volcanic  peaks  and  ranges  of  hills.  The  precipi- 
tation in  the  form  of  snow  is  heavy  in  these  mountains.  Snowslides  fre- 
quently rush  down  the  lateral  ravines  into  the  main  valleys  in  such  masses 
that  often  they  do  not  entirely  melt  during  the  summer,  although  situated 
so  far  south. 

The  mountains  consist  of  a  mass  of  upheaval  due  to  igneous  eruptions 
through  sedimentary  beds  which  have  been  somewhat  metamorphosed. 
This  makes  it  easy  to  recognize  matter  from  tlie  mountains  as  compared 
with  the  unaltered  sediments  of  the  adjacent  plains.  The  mass  of  upheaval 
has  been  deeply  dissected  by  a  radiating  system  of  streams,  so  that  the 
mountains  now  consist  of  centrally  connected  ridges  separated  by  profoimd 
canyons  ending  above  in  rather  narrow  cirques,  the  ridges  being  only  a  few 
feet  wide  on  their  tops  and  having  their  lateral  slopes  steep  as  talus  will  lie, 
and  often  precipitous.  Many  of  these  slopes  are  so  steep  that  lateral 
moraines  must  have  slid  down  the  mountain  sides  as  fast  as  the  glaciers 
melted,  but  here  and  there  are  broader  parts  of  the  ridges,  or  shelves  on 
their  sides,  or  gutter  slopes,  where  morainal  matter  could  lodge. 

The  evidence  is  conclusive  that  these  valleys  were  once  filled  by 
extensive  glaciers. 

Glacial  scratches. — Altliougli  tlie  local  rocks  resist  chemical  decomposition 
very  well,  they  fracture  readily.  Hence,  only  here  and  there  does  the 
exposed  rock  in  place  preserve  the  glacial  scratches.  Many  places  are 
covered  with  a  talus  which  sho,ws  slabs  up  to  4  feet  in  length  that  are  well 


LA  PLATA  MOUNTAINS.  339 

glaciated  on  one  side.     Fresh  exposures  from  beneath  the  soil  reveal  gla- 
ciated rock  up  to  near  the  top  of  the  secondary  ridges. 

Moraines. — Qu  thc  stecpcr  lateral  slopes  of  the  valleys  there  is  no 
moraine  stuff.  On  gentler  slopes  there  is  a  thin  sheet  or  scattering  of 
erratics.  No  distinct  ridges  or  terraces  were  observed,  except  one  on  a 
shelf  of  the  mountainside  situated  in  the  valley  of  the  East  Mancos  River 
about  3  miles  from  its  head,  and  250  feet  above  the  valley;  also  two  at 
Helmet  Peak.  This  peak  is  the  highest  peak  of  a  high  ridge  which  sepa- 
rates the  East  Mancos  and  West  Mancos  valleys.  To  the  west  (in  lee  of) 
this  peak,  and  perhaps  50  feet  below  the  summit,  are  two  moraines,  one 
lateral  to  each  valley.  Most  of  the  material  is  rather  fine  and  well  gla- 
ciated. The  upper  surface  of  the  moraines  conforms  to  the  slopes  of  the 
mountain,  here  quite  gentle.  These  terraces  are  shown  to  be  moraines, 
not  only  by  the  glaciation  of  the  stones,  but  also  by  the  fact  that  the 
local  rock  is  igneous  (hornblendic  trachyte  of  Hayden)  while  most  of  the 
glaciated  stones  are  of  quartzite  and  other  erratic  material.  The  upper 
part  of  the  peak  is  so  weathered  and  shattered  that  I  can  not  be  sure 
whether  it  was  ever  glaciated  or  not;  hence  it  is  uncertain  whether  these 
moraines  were  pushed  out  laterally  at  the  surface  of  the  ice  or  were  formed 
subglacially  as  tail  to  the  peak  as  crag,  at  a  time  when  the  ice  in  the  two 
valleys  rose  above  the  ridge  that  divides  them.  This  is  about  600  feet 
above  the  valley  of  the  East  Mancos. 

In  the  upper  3  miles  of  the  valley  of  East  Mancos  River  there  are  a 
number  of  small  retreatal  or  terminal  moraines  in  the  bottom  of  the  valley, 
which  here  is  U-shaped,  but  becomes  V-shaped  nearer  the  plains.  After 
entering  the  plains  the  stream  flows  in  a  valley  of  erosion  in  sedimentary 
beds.  This  valley  grows  wider  and  wider  up  to  near  a  mile  in  breadth 
at  Mancos. 

Lateral  and  terminal  moraines  would  naturally  form  where  the  stream 
emerges  from  the  mountains,  but  the  slope  here  is  very  steep,  and  most  of 
the  moraine  stuff  appears  to  have  become  a  part  of  the  glacial  gravel  or 
has  been  left  much  scattered  The  upper  valley  of  La  Plata  River  is 
considerably  broader  than  that  of  the  East  Mancos.  It  contained  a  much 
larger  glacier,  which  has  left  moraines  arranged  about  like  those  of  the 
valley  already  described. 

Glacial  gravels — Large  ovcrwash  or  frontal  aprons  of  water-rounded  gravel. 


340  GLACIAL  GRAVELS  OP  MAINE. 

cobbles,  bowlderets,  and  bowlders  up  to  5  feet  in  diameter  begin  2  to  4 
miles  from  the  liead  of  these  streams  and  extend  15  or  more  miles  down 
the  valleys.  The  size  of  the  stones  grows  smaller  as  we  go  below  the 
principal  terminal  moraines.  There  is  a  large  terrace  in  the  valley  of  La 
Plata  River  a  little  below  where  it  emerges  from  the  mountains,  which  is 
composed  in  large  part  of  very  coarse  matter  and  appears  like  a  water- 
.  washed  terminal  moraine.  The  bowlders  were  probably  rounded  by  the 
waves  of  a  Tertiary  lake. 

In  the  narrower  part  of  the  East  Mancos  Valley  the  plain  of  water- 
rounded  matter  is  50  to  150  feet  wide  and  3  to  8  feet  deep.  While  the 
stones  of  the  moraines  show  unequal  wear  into  subaugular  forms,  and  some 
faces  with  little  wear,  these  are  polished  quite  equally  on  all  sides  and  have 
much  rounder  shapes.  Some  parts  of  the  valley  have  been  worked  as 
gold  placers,  and  thus  it  has  been  revealed  that  underneath  the  gravel  is 
glaciated  rock,  hollowed  out  into  numerous  rather  shallow  potholes.  The 
miners  affirm  that  most  of  the  gold,  which  is  quite  coarse,  is  found  in  coarse 
gravel  near  the  bed  rock,  and  not  in  the  bottoms  of  the  potholes  and 
hollows,  but  on  level  rock  between  tliem.  This  proves  that  the  currents 
were  swiftest  where  the  potholes  and  basins  now  are.  The  gravels  are 
most  easily  interpreted  as  due  to  swift  subglacial  streams,  either  beneath  the 
ice  or  in  front  of  the  ice  as  they  rushed  from  the  mouths  of  their  tunnels. 
The  stream  has  eroded  a  portion  of  the  original  gravel  deposit  and 
rearranged  a  portion  as  a  new  flood-plain. 

Summary. — Tlic  priuclpal  vallcys  of  La  Plata  Mountains  were  filled  by 
glaciers  600  or  more  feet  deep.  A  verj'  large  proportion  of  the  transported 
matter  was  acted  upon  by  the  subglacial  streams,  with  the  result  that  for 
many  miles  the  valleys  are  strewn  with  frontal  plains  of  glacial  sediments, 
though  mixed  probably  with  considerable  stream  wash.  The  moraines 
are  of  less  size  than  the  ordinary  for  glaciers  of  such  length.  Hayden's 
Atlas  of  Colorado  shows  no  moraines  among  La  Plata  Movmtains.  My 
exploration  of  the  mountains  was  confined  to  two  valleys. 

LAS  ANIMAS  VALLEY. 

Las  Animas  River  rises  in  the  heart  of  the  San  Juan  Mountains  and 
flows  southward  into  New  Mexico,  whei'e  it  joins  the  San  Juan  River, 
which  it  is  the  principal  tributary.     Its  head  waters  occupy  a  radiating 


LAS  ANIMAS  VALLEY.  ,  341 

system  of  deep  valleys  bordered  by  mountains  rising  to  elevations  of  from 
11,000  to  14,000  feet.  Over  the  upper  part  of  this  valley,  covering  500 
square  miles,  the  precipitation  is  probably  greater  than  over  any  other 
equal  area  in  Colorado.  Every  cirque  and  lateral  valley  contained  its 
glacier,  which  was  tributary  to  that  of  a  main  valley. 

The  rocks  of  this  region  are  largely  volcanic,  and  in  general  weather 
easily,  either  by  chemical  decomposition  or  by  fracture.  Grlacial  scorings 
are  seldom  found  on  exposed  rock  surfaces.  Excavations  made  in  con- 
sti'ucting  roads  over  the  mountain  passes  and  to  the  mines  show  that  in  the 
lai'ger  cirques  and  passes  the  rock  is  glaciated  up  to  about  12,000  feet. 
Mining  excavations  have  been  made  at  higher  elevations,  but  none  of  them 
visited  by  me  are  in  such  situations  that  we  could  expect  them  to  show  the 
glaciated  rock.  Hence,  while  it  is  probable  that  the  glaciers  extended  nearly 
or  quite  to  the  tops  of  the  higher  basins,  I  have  as  yet  no  glacial  scratches 
to  prove  it. 

The  scratches  iu  the  lateral  valleys  are  parallel  with  these  valleys,  but 
as  we  descend  them  we  come  to  where  the  scratches  are  parallel  with  the 
main  valleys  and  transverse  to  the  lateral.  Obviously  if  we  can  determine 
the  height  above  the  main  valleys  that  these  sci'atches  parallel  with  them 
reach,  we  shall  know  the  depth  of  the  great  valley  glaciers.  Such  scratches 
I  have  from  time  to  time  observed,  and  by  degrees  the  upper  limit  was 
raised,  till  now  it  is  proved  that  the  main  Las  Animas  glacier  was  more  than 
1,000  feet  deep  at  Silverton  and  at  least  1,500  feet  at  a  point  5  miles  south 
of  Silverton.  This  was  the  main  outlet  of  the  ice  of  this  region.  The 
tributary  glaciers  reached  to  the  tops  of  cols  12,000  feet  high,  and  2jerhaps 
higher.  Thus  at  Stony  Pass,  a  pass  from  the  Rio  Grande  over  the  Conti- 
nental Divide  to  Las  Animas  Valley  via  Cunningham  Grulch,  I  found  well- 
glaciated  rock  within  100  feet  horizontally  from  the  top  of  the  pass,  and 
on  both  slopes.  On  each  side  were  peaks  of  the  range  rising  1,000  feet  or 
more  above  the  pass.  It  is  thus  proved  that  the  flow  took  place  from  the 
very  top  of  the  ridge  down  two  valleys  iu  opposite  directions.  The  supply 
probably  came  laterally  from  the  adjacent  peaks. 

Nowhere  in  these  steep  mountains  have  I  found  prominent  lateral 
moraines  in  the  form  of  ridges  or  terraces.  Many  of  the  slopes  are  so  steep 
that  no  moraine  stuff  could  remain  perched  on  them.  The  volcanic  rocks 
have  often  weathered  and  formed  slides  of  talus  1,000  to  2,000  feet  high. 


342  GLACIAL  GRAVELS  OF  MAINE. 

On  the  gentler  slopes  there  is  a  body  of  drift  that  forms  a  complex  problem. 
Near  the  underlying  rock  almost  all  the  stones  show  considerable  attrition, 
the  original  forms  due  to  weathering  and  fracture  having  been  somewhat 
changed  by  a  subsequent  process  of  polishing.  The  coarser  stones  are 
mixed  with  some  fine  matter,  thus  forming  a  mass  somewhat  resembling  the 
till  of  New  England.  Approaching  the  surface,  we  find  an  increasing  pro- 
portion of  rain  wash  and  talus.  Some  of  the  worn  stones  are  distinctly 
glaciated.  On  steep  slopes  where  there  has  been  much  sliding  and  soil-cap 
movement,  the  stones  are  subject  to  some  wear,  and  thus  the  interpretation 
of  the  sheets  of  drift  on  the  wooded  slopes  of  these  mountains  is  difficult. 
In  many  places  there  are  bowlders  in  this  drift  that  have  plainly  come  from 
a  distance;  hence,  in  part  at  least,  it  is  of  glacial  origin.  Naturally  where 
the  snow  covered  the  mountains  almost  to  their  summits  there  would  be 
much  matter  borne  onward  in  the  lower  part  of  the  ice.  I  leave  it  as  an 
open  question  how  far  the  drift  sheets  of  the  gentler  slopes  of  these  moun- 
tains were  deposited  subglacially  and  how  far  they  are  a  lateral  moraine, 
left  at  the  margin  of  the  ice  as  it  melted  and  sank  to  lower  levels. 

The  two  forks  of  Mineral  Creek  come  together  at  right  angles.  The 
valley  of  the  South  Fork  is  the  larger.  At  a  time  when  the  ice  had 
retreated  from  Las  Animas  Valley,  also  from  the  North  Fork  of  Mineral 
Creek,  a  glacier  still  continued  to  flow  in  the  valley  of  the  South  Fork.  It 
flowed  across  the  valley  of  the  North  Fork  and  abutted  against  Red  Moun- 
tain, where  it  deposited  a  terminal  moraine  100  feet  high  near  the  railroad 
from  Silverton  to  Ironton.  Above  Silverton  there  are  a  number  of  terminal 
(retreatal)  moraines,  more  or  less  water-washed.     All  are  small. 

About  a  mile  north  of  the  city  of  Durango  a  terminal  moraine  extends 
across  the  valley  of  Las  Animas  River,  here  about  one-third  of  a  mile  wide. 
It  forms  a  low  ridge  rising  10  to  30  feet  above  the  sedimentary  matter  that 
covers  its  flanks.  It  is  thus  proved  that  at  one  time  the  ice  flowed  to  or 
beyond  Durango  at  an  elevation  of  about  6,000  feet.  I  have  not  explored 
the  valley  below  that  point  sufficiently  to  know  the  extreme  limit  of  the 
ice.  From  Durango  to  Silverton  it  is  45  miles,  and  to  the  head  of  the  Las 
Animas  65  to  70  miles.  Assuming  that  the  ice  surface  was  at  the  top  of  the 
mesa  near  Durango  and  rose  1,500  feet  above  Silverton,  we  have  an  average 
surface  gradient  of  about  120  feet  per  mile. 

Fi-om  where  Las  Animas  River  emerges  from  the  mountains  it  flows  in 


EIO  GRANDE  AND  SAN  MIGUEL  VALLEYS.         343 

a  valley  1  to  2  miles  wide  wliicli  extends  for  12  miles  and  then  suddenly 
narrows  to  one-third  of  a  mile.  It  is  at  this  point  that  the  terminal  (or 
retreatal)  moraine  near  Durango  is  formed.  North  of  this  point  a  sheet  of 
water-romided  matter  containing  many  bowlderets  and  bowlders  extends 
for  many  miles  up  Las  Animas  Valley.  At  the  melting  of  the  ice  at  this 
point  the  moraine  and  overwash  j)lain  formed  a  barrier  or  dam  across  the 
valley,  and  in  the  broad  valley  to  the  north  there  gathered  a  shallow 
lake.  Into  this  temporary  lake  there  came  a  broad  sheet  of  sand  and  silt. 
It  is  now  practically  drained  b}^  the  river  cutting  down  through  the  dam  at 
Durango. 

The  valley  of  Las  Animas  River  for  many  miles  in  the  mountains  con- 
tains a  body  of  water-rounded  glacial  gravel,  now  deeply  eroded,  so  that 
in  many  places  a  little  terrace  here  and  there  is  all  there  is  left  of  a  deposit 
once  30  to  70  feet  deep.  In  other  places,  as  at  Silverton,  this  gravel  plain 
is  still  well  developed. 

It  is  thus  proved  that  a  glacier  1,500  or  more  feet-  deep  originated  in 
Las  Animas  Valley  and  flowed  70  or  more  miles  southward.  For  many 
miles  it  was  a  mile  or  more  in  breadth.  It  left  rather  scanty  moraines  for 
a  glacier  of  its  size,  but  a  ver}^  large  amount  of  water-transported  matter. 
Its  distal  extremity  reaches  37°  15'  north  latitude  or  less,  an  elevation 
somewhat  below  6,500  feet. 

Glaciers  occupied  the  upper  valleys  of  Los  Pinos,  San  Juan,  Navajo, 
Chama,  and  other  rivers  of  the  western  slopes  of  the  San  Juan  Mountains, 
but  I  have  not  explored  them  sufficiently  for  notice  here. 

UPPER   RIO   GRANDE   VALLEY. 

A  very  large  glacier  must  have  occupied  the  upper  Rio  Grande 
Valley.  A  large  number  of  basins  and  valleys  open  down  into  it  from  the 
Continental  Divide,  all  well  glaciated.  My  explorations  were  near  the 
head  waters,  and  do  not  permit  description  of  the  lower  end  of  this  large 
glacier. 

VALLEY  OF  THE  SAN  MIGUEL  RIVER. 

The  main  river  flows  in  a  box  canyon  deeply  ei'oded  in  sedimentary 
rocks  which  are  nearly  horizontally  bedded.  Approaching  the  mountains, 
Ave  find  the  branches  occupying  valleys  eroded  down  through  sheets  of 
volcanic  lavas  and  tuffs  into  sedimentary^  beds,  while  in  the  higher  cirques 


344  GLACIAL  GRAVELS  OP  MAINE. 

and  valleys  we  find  the  volcanic  rock  alone.  The  mountains  rise  to- 
heights  varying  from  11,000  to  near  14,000  feet.  They  receive  the  first 
onset  of  the  Pacific  winds,  and  the  precipitation  is  great.  The  valley  of 
the  North  Fork  was  occupied  by  a  glacier  which  left  a  terminal  moraine 
near  Keystone,  about  5  miles  west  from  Telluride.  Many  of  the  slopes  are 
so  steep  that  moraines  would  slide  at  once  down  to  the  bottoms  of  the 
valleys,  but  in  many  places  there  is  a  sprinkling  of  erratics  on  the  sides  of 
the  valleys.  Ophir  and  Trout  Lake  basins,  on  the  South  Fork  of  the  San 
Miguel,  each  contained  glaciers  which  left  moraines  in  the  bottoms  of  their 
valleys,  but  their  gathering-grounds  were  small  and  they  appear  to  have 
been  less  than  8  miles  in  length. 

The  bottoms  of  the  valleys  of  the  San  Miguel  River  and  its  three 
pi-incipal  tributaries  were  once  covered  with  a  deep  body  of  well-rounded 
gravel  and  coarser  matter  up  to  bowlders.  This  original  deposit  has  now 
been  eroded  to  depths  of  30  to  70  feet,  leaving  portions  of  the  old  plain  as 
terraces  on  the  steep  sides  of  the  canyons,  the  so-called  high  bars  of  the 
placer  miners.  These  terraces,  growing  finer  by  degrees,  extend  40  miles 
from  the  mountains — how  much  more  I  do  not  know.  They  in  part  consist 
of  Tertiary  drift.  In  these  valleys  the  overwash  apron  of  glacial  gravel  far 
exceeded  in  bulk  the  moraines.  The  glacial  gravel  is  found  all  the  way 
from  the  moraines  up  to  the  mountain  basins. 

VALLEY  OF  THE  UNCOMPAHGRE  RIVER. 

This  stream  heads  against  Las  Animas  River  and  flows  in  the  oppo- 
site direction  northward,  and,  having  cut  deep  canyons  through  the  Mount 
Sneffles  Range,  emerges  from  the  mountains  a  few  miles  below  Ouray. 
■South  of  Ouray  the  very  ancient  quartzites  are  intensely  glaciated,  but 
retain  an  uneven  and  hummocky  surface.  The  gentler  slopes  of  the  moun- 
tains carry  sheets  of  drift  which  in  composition  and  character  resemble 
those  of  the  upper  Las  Animas  Valley  above  described.  Two  V-shaped 
valleys  join  at  Ouray,  below  which  point  the  valley  is  U-shaped  and  soon 
broadens  to  a  mile  or  more  near  Ridgwa}'^,  where  the  Dallas  branch  joins 
the  main  stream.  Here  a  broad  series  of  ridges  and  heaps  of  erratics 
extends  obliquely  across  the  valleys  of  both  branches  just  below  their  junc- 
tion. Glaciers  came  down  both  valleys  and  left  these  moraines,  which  are 
more  than  a  mile  long  and  near  half  a  mile  wide,  rising  in  places  to  150  feet 


UPPER  ARKANSAS  VALLEY.  345 

in  height.  The  moraines  have  been  deeply  cut  by  the  river.  I  have  not 
been  able  to  find  any  moraines  below  Dallas,  and  probably  these  moraines 
between  Ridgway  and  Dallas  mark  the  extreme  advance  of  the  ice. 

The  bottom  of  the  valley  from  Ouray  northward  40  miles  to  beyond 
Montrose  is  covered  with  rounded  and  rolled  gravel  and  coarser  matter. 
In  places  this  overwash  sheet  is  more  than  a  mile  wide.  The  fact  that  the 
same  sort  of  gravel  plain  extends  for  12  miles  above  the  outermost  moraines 
proves  that  the  subglacial  streams  during  the  retreat  for  a  long  time  contin- 
ued to  pour  out  glacial  gravel  into  the  open  valley  in  front  of  the  ice. 
Where  observed  this  gravel  is  rather  horizontally  stratified  and  shows  none 
of  the  appearance  of  the  reticulated  kame  ridges.  The  reti-eat  of  the  ice 
ajDpears  to  have  been  rather  gradual,  since  there  are  only  small  retreatal 
moraines  in  the  lower  parts  of  the  valley.  The  sides  of  the  main  valley 
show  a  sprinkling  of  erratics,  except  where  precipitous. 

The  Uncompahgre  glacier  reached  only  8  miles  beyond  the  mountains, 
but  transported  a  very  large  amount  of  morainal  matter,  and  also  glacial 
sediments.  The  base  of  the  terminal  moraine  at  Ridgway  is  at  7,000  feet 
elevation. 

There  were  numerous  glaciers  in  the  valleys  tributary  to  the  Gunnison 
River,  some  of  them  of  large  size. 

UPPER  ARKANSAS  VALLEY. 

The  glacial  deposits  of  this  valle}^  were  first  described  by  the  Hayden 
Survey,  and  later  by  Emmons  in  his  Leadville  monograph.^  It  is  impos- 
sible to  do  justice  to  this  interesting  valley  without  going  into  detail  more 
than  is  here  practicable,  and  only  a  few  points  will  be  noted.  The  first 
thing  that  attracts  attention  is  the  enormous  size  of  the  moraines  which  the 
glaciers  that  originated  in  the  Sawatch  Range  have  left  across  the  main 
valley.  The  Arkansas  Valley  from  Leadville  southward  to  Salida  is  from 
2  to  4  miles  wide  between  the  bases  of  the  steep  mountains.  The  lateral 
g'laciers  flowing  down  from  the  mountains  did  not  fill  this  broad  valley — at 
least  they  did  not  for  a  long  time  during  the  last  part  of  the  ice  period — 
and  thus  left  moraines  at  the  sides  and  in  front  of  their  valleys.  Some  of 
these  moraines  cover  several  square  miles  and  are  up  to  1,000  feet  in  height. 

1  Geology  and  Mining  Industry  of  Leadville,  with  atlas,  Mon.  V.  S.  Geol.  Survey,  vol.  12,  pp.  40-42,, 
1886. 


346  GLACIAL  GEAYELS  OF  MAINE. 

The  lateral  moraines  form  large  ridges  or  terraces  upon  the  mountain  sides. 
The  glaciers  from  the  west  side  of  the  valley  were  much  larger  than  those 
from  the  east.  It  is  possible  that  at  one  time  a  broad  glacier  occupied  the 
whole  Arkansas  Valley,  but  my  own  observations  leave  the  matter  in  doubt 
as  to  the  last  glacial  period.  A  good  place  for  observing  these  phenomena 
is  in  the  valley  of  Box  Creek,  and  its  tributaries,  Willow  Gulch  and  Har- 
rington Gulch.  They  originate  on  the  eastern  slopes  of  Mount  Elbert  and 
flow  southeastward  and  eastward  into  the  Arkansas  River  near  Hayden 
station,  on  the  Denver  and  Rio  Grande  Railroad,  about  12  miles  below 
Leadville.  Near  here,  on  both  sides  of  the  Arkansas  River,  are  well  exhib- 
ited two  types  of  valleys,  the  broad  U-shaped  valleys  that  were  occupied 
by  glaciers  while  their  margins  were  being  piled  high  with  morainal  and 
sedimentary  drift,  and  the  nan-ower  valleys,  generally  V-shaped,  due  to 
recent  erosion  of  a  once  continuous  mass.  The  Arkansas  River  is  here 
bordered  by  a  rather  level  plain  of  glacial  sediments  about  a  mile  wide. 
Extending  west  from  tliis  plain  is  the  plain-like  valley  of  Box  Creek  and  its 
tributaries,  from  one-fourth  mile  to  near  a  mile  in  width.  Near  the 
Arkansas  they  are  bordered  by  mesas  of  glacial  sediments  ending  in  steep 
bluffs  150  to  250  feet  high,  while  as  we  near  the  mountains  they  are  bor- 
dered by  bluff-like  lateral  moi'aines.  These  moraines  prove  conclusively 
that  the  upper  portions  of  these  valleys  were  filled  by  glaciers  that  origi- 
nated in  the  large  cirques  of  Mount  Elbert.  If  the  glaciers  had  stopped  at 
the  base  of  the  mountain  they  ought  to  have  deposited  terminal  moraines. 
Instead,  a  U-shaped  valley  of  the  same  character  as  those  bordered  by 
lateral  moraines  extends  continuously  to  the  Arkansas  Valley,  which  is  also 
free  from  moraines  at  this  place.  The  conclusion  follows  that  three  glaciers 
originated  on  Mount  Elbert  and  united  near  its  base  to  form  a  single  tongue, 
and  it  in  turn  united  with  a  glacier  which  filled  the  bottom  of  the  Arkansas 
Valley  for  many  miles  below  Leadville  over  a  varying  breadth  of  one-half 
mile  to  somewhat  more  than  a  mile.  This  main  glacier  received  many 
tributaries  from  the  adjoining  mountains.  Between  the  successive  lateral 
valley  glaciers  and  the  main  glacier  that  extended  along  the  axis  of  the 
Arkansas  Valley  there  were  open  spaces  bare  of  ice  into  which  the  subgla- 
cial  streams  of  the  lateral  glaciers  poured  and  deposited  overwash  aprons 
of  glacial  sediments.  Sometimes  these  alluvial  mesas  end  next  the  river 
bluffs  in  sand  or  fine  clay  and  rock  flour,  proving  that  here  were  glacial 


UPPER  ARKANSAS  VALLEY.  347 

lakes.  In  other  places  coarse  gravel  continues  rig-ht  up  to  the  bluff  mark- 
ing the  former  margin  of  the  Arkansas  glacier,  proving  that  the  waters  that 
were  poured  from  above  into  these  open  spaces  found  ready  exit  into  the 
subglacial  waterways  of  the  main  glacier,  and  in  such  cases  the  allu^dal 
mesa  was  formed  subaerially,  ending  in  a  steep  bluff  because  piled  against 
the  side  of  the  Arkansas  glacier.  The  symmetry  of  the  U-shaped  valleys 
bordered  by  bluffs  of  glacial  sediments  or  moraines  is  better  preserved  in 
case  of  the  shorter  glaciers.  The  enormous  amount  of  morainal  matter 
brought  down  by  the  longer  lateral  glaciers  formed  dams  that  obstructed 
their  flow  and  forced  them  to  wander  in  search  of  an  outlet.  On  the  great 
moraines  of  the  Lake  Creek  glacier,  which  are  situated  noi'theast  of  Twin 
Lakes,  and  which  formed  in  part  the  lateral  moraine  of  the  Willow  Gulch 
glacier  of  Mount  Elbert,  we  find  remarkably  sudden  transitions  between 
morainal  ridges  and  glacial  sediments.  The  region  has  been  prospected  by 
placer  miners,  and  thus  were  revealed  the  following  facts :  At  the  top  of  the 
great  moraine  a  shaft  was  dug  98  feet  in  gritty  clay.  The  digging  is  on  a 
small  level  place.  Two  hundred  feet  west  a  steep  ridge  rises  perhaps  50 
feet  above  this  flat  and  is  composed  of  bowlders  and  other  coarse  moraine 
stuff.  In  sevei'al  places  are  mounds  or  small  mesas  that  rise  50  to  100 
feet  above  the  rest  of  the  moraine,  which  are  proved  by  tunnels  and  shafts 
to  be  composed  of  clay  and  fine  sand.  These  local  masses  of  fine  sedi- 
ments in  the  midst  of  moraines  were  probabl)'  deposited  in  small  glacial 
lakes  like  those  of  the  marginal  region  of  the  Malespina  glacier,  described 
by  Russell.  The  retreat  of  the  Mount  Elbert  glaciers  here  described  seems 
to  have  been  quite  rapid  until  we  reach  the  base  of  the  mountain.  Here 
the  principal  tributar}^,  the  Willow  Gulch  glacier,  formed  several  frontal 
alluvial  terraces  at  different  elevations.  Going  up  the  mountain  from  this 
place  we  find  only  a  few  small  deposits  of  glacial  gravel,  the  streams  of 
the  shortening  glacier  becoming  too  feeble  to  transport  much  sediment. 
But  the  shrinking  of  the  glacier  is  marked  by  a  series  of  retreatal  moraines 
that  are  found  every  half  mile  or  so  up  to  timber  line.  Near  the  base  of 
the  mountain  the  morainal  matter  is  nearly  all  well  glaciated,  and  often 
contains  so  much  rock  flour,  clay,  and  fine  ddbris  as  to  resemble  the  till  of 
New  England.  Going  up  the  mountain  we  find  the  glaciation  becoming 
less  intense,  till  at  the  last  we  find  rock  piles  in  the  characteristic  form  of 
moraines  with  few  signs  of  attrition.     This  delineation  is  only  intended  to 


348  GLACIAL  GRAVELS  OP  MAINE. 

describe  the  last  part  of  the  last  glacial  period.  Earlier  the  lateral  g-laciers 
may  have  been  confluent  in  an  ice-sheet  which  covered  all  the  Arkansas 
Valley  from  mountain  to  mountain. 

We  also  here  have  the  same  alluvial  aprons  we  find  in  the  San  Juan 
valleys.  Not  being-  confined  in  a  narrow  valley,  they  take  the  characteris- 
tic form  of  the  alluvial  cone  radiating  from  the  terminal  moraines.  The 
aprons  are  somewhat  distinct  as  far  south  as  Buena  Vista;  then  they  merge 
into  a  plain  of  coarse  water-rounded  matter  that  occupies  the  valley  to  a 
point  beyond  Pueblo,  except  where  it  has  disappeared  owing  to  erosion. 
Some  of  this  water-rolled  matter  came  from  the  Wet  Mountains  and  the 
Sangre  de  Christo  Range,  but  most  of  it  came  down  the  main  Arkansas 
River. 

The  general  law  of  frontal  aprons  of  glacial  gravel  is  that  they  become 
finer  as  we  go  away  from  the  principal  terminal  moraines.  From  tlie  mouth 
of  Lake  Creek  to  near  Buena  Vista  there  are  multitudes  of  water-rounded 
bowlders  in  the  plain  of  rolled  matter  that  here  covers  the  eastern  part  of 
the  Arkansas  Valley.  Many  of  them  are  from  6  to  10  feet  in  diameter. 
Of  course  it  is  not  meant  to  assert  that  they  were  not  glaciated  before 
being  worn  by  the  action  of  water.  Below  this  point  the  material  becomes 
finer. 

Emmons  has  described  the  so-called  "Lake  beds"  at  Leadville.  I 
have  discovered  there  were  local  glacial  lakes  not  far  from  Twin  Lakes  and 
at  other  points  in  the  valley.  They  formed  between  the  tongues  of  ice 
that  then  projected  into  the  valleys  and  formed  dams  across  it  extending  to 
the  main  valley  glacier. 

PIKES   PKAK   RANGE. 

Glaciers  formed  in  the  valleys  of  some  of  the  branches  of  West  Beaver 
Creek  that  were  3  to  4  miles  in  length;  also  in  the  deep  canyon-like  valley 
that  extends  north  from  the  peak,  but  I  have  not  explored  the  latter  system- 
atically. A  glacier  formed  on  the  south  slopes  of  Pikes  Peak  in  the  valley 
of  East  Beaver  Creek.  Its  terminal  moraines  form  the  dams  that  confine 
the  Seven  Lakes.  The  morainal  matter  is  itself  somewhat  sandy  and 
water-washed,  but  the  valley  below  here  contains  no  overwash  apron  of 
glacial  gravel.  Probably  there  was  some  rather  fine  sediment,  but  it  has 
now  disappeared  by  erosion  on  a  steep  slope.  The  length  of  this  glacier 
was  not  far  from  3  miles. 


UPPEE  ARKANSAS  YALLEY.  349 

Lake  Moraine  is  situated  in  a  valley  descending  from  the  col  between 
Pikes  Peak  and  Bald  Mountain.  A  glacier  but  little  more  than  a  mile  in 
length  occupied  this  basin.  It  left  prominent  lateral  moraines  near  200  feet 
above  the  bottom  of  the  basin,  and  formed  a  massive  terminal  moraine  near 
one-fourth  of  a  mile  long  and  100  or  more  feet  deep.  There  is  a  depres- 
sion across  the  terminal  moraine,  in  which  a  stream  flows.  No  glacial 
gravel  appears  in  the  valley  below,  which  is  very  steep,  so  that  the  over- 
wash  of  the  glacier  would  soon  be  eroded.  In  the  bottom  of  the  depres- 
sion in  the  terminal  moraine  appears  a  mass  of  fine  sediment,  mixed  with 
occasional  bowlders,  which,  under  the  microscope,  is  seen  to  consist  of  glacial 
rock  flour. 

This  little  glacier  was  situated  between  10,000  and  11,000  feet  eleva- 
tion. The  snowfall  of  this  range  is  much  less  than  that  of  the  Continental 
Divide.  The  temperature  was  low  even  in  summer.  The  glacial  waters 
flowed  so  sluggishly  that  even  much  of  the  rock  flour  did  not  get  beyond 
"the  terminal  moraine. 

A  little  glacier  formed  on  the  east  side  of  Pikes  Peak  and  formed  a 
diminutive  moraine  which  now  holds  in  a  lakelet. 

SOUTH   PARK. 

A  number  of  glaciers  originated  in  the  Mosquito  Range  and  flowed 
eastward  into  the  South  Park.  Some  of  them  were  near  10  miles  in  length. 
They  left  moderate-sized  moraines  and  plains  of  glacial  gravel  that  extend 
15  miles  down  into  the  open  park.  These  plains  are  marked  "scattered 
drift"  on  Hayden's  maps.  In  most  cases  where  I  have  had  opportunity  to 
examine  a  region  thus  marked  they  end  in  the  mountains  in  a  glaciated 
region  and  are  frontal  plains  of  glacial  sediments.  The  proportion  of 
glacial  gravel  to  moraines  is  here  probably  greater  than  in  the  Ai-kansas 
Valley. 

ROAEING   PORK. 

The  valley  of  the  Middle  Branch  of  the  Roaring  Fork  contained  a 
g-lacier  15  or  more  miles  in  length.  The  moraines  of  this  glacier  can  be 
seen  from  the  Colorado  Midland  Railway.  Lake  Ivanhoe,  along  this  rail- 
way, is  held  in  by  a  morainal  dam.  Below  the  terminal  moraines  the 
valle}^  was  left  covered  with  a  deep  sheet  of  water-rolled  sediments  which 
.has  now  been  eroded  to  a  depth  of  30  or  more  feet. 


350  GLACIAL  GEAVELS  OF  MAINE. 

The  valleys  tributary  to  the  South  Branch  of  the  Roaring  Fork  were 
occupied  by  glaciers  to  a  point  not  far  below  Aspen.  They  left  moderate- 
sized  moraines  and  a  sheet  of  glacial  gravel  that  extends  for  30  or  more 
miles  down  the  valley.  In  the  valley  of  Hunters  Creek,  east  of  Aspen,  a 
line  of  perched  bowlders  marks  the  upper  limit  of  the  ice. 

ROCK    CREEK. 

This  stream  flows  for  a  few  miles  west,  and  then  north,  and  drains  the 
western  slopes  of  the,  Elk  Mountains.  Grlaciers  extended  12  miles  down 
the  valley  and  have  left  numerous  rather  small  moraines.  The  amount  of 
glacial  gravel  in  the  valley  is  less  than  in  most  valleys  of  the  westei-n  slope 
having  so  large  a  drainage  surface. 

When  one  follows  the  Roaring  Fork  down  to  its  junction  with  the 
Eagle  River  to  form  the  Grand  River,  and  thence  down  to  the  Colorado,  he 
will  appreciate  what  a  tremendous  weapon  the  glaciers  furnished  the  present 
rivers.  The  plains  of  rolled  gravel  and  cobbles  left  by  the  glaciers  have 
helped  protect  the  higher  slopes  of  the  mountains  from  erosion,  but  the 
streams  have  rolled  them  down  to  the  Gulf  of  California  with  fatal  effect 
on  the  plains  and  plateaus.  In  time  of  high  water  the  ceaseless  rattle  and 
roar  of  those  stones  as  the  Grand  River  surges  them  on  is  one  of  the  most 
astonishing  phenomena  of  the  mountain  slopes.  If  the  ear  be  held  near 
the  water  or  against  a  boat,  one  hears  a  roar  as  of  distant  thunder  mingled 
with  the  sharper  click  of  near-by  stones.  After  that  the  profoimd  canyons 
of  the  plateau  region  are  no  mystery. 

ESTES    PARK. 

Several  glaciers  5  to  10  miles  long  flowed  down  into  Estes  Park. 
They  left  very  large  lateral  moraines  near  where  they  enter  the  park,  and 
smaller  terminal  moraines  at  about  6,100  feet  elevation.  The  retreat  of 
the  ice  is  marked  by  a  series  of  terminal  moraines,  which  are  found  at 
intervals  all  the  way  up  to  the  ultimate  basins  in  which  the  glaciers  origi- 
nated. Nowhere  have  I  seen  such  great  masses  of  bowlders  showing  few 
or  no  signs  of  glaciation  and  without  admixture  of  fine  material,  as  some 
of  these  retreated  moraines  exhibit.  They  are  locally  known  as  bowlder 
fields,  and  are  often  almost  impassable  even  to  men  on  foot,  owing  to  the 
large  size  of  the  bowlders.     They  are   mostly  of  granite   and  are  more 


VALLEY  OF  SALMON  RIVER.  351 

r.iigulMi-  than  ordinary  bowlders  of  decomposition.  The  proportion  of 
glacial  g-ravel  to  morainal  matter  is  smaller  than  in  any  other  g-laciers  of 
the  same  size  that  I  have  fonnd  in  Colorado.  • 

In  the  higher  cirques  of  this  reg-ion  there  are  numerous  fields  of  per- 
petual snow.  One  of  these  in  a  valle}^  lyi"g  on  the  northeast  slopes  of 
Hague's  Peak  is  consolidated  to  ice  and  exhibits  transverse  crevasses.  It  is 
plainly  sliding,  if  not  flowing,  down  the  mountain  side.  It  appears  so 
much  like  a  true  glacier  that  I  have  named  it  the  Hallett  glacier,  after  the 
discoverer. 

VALLEY    OF    THE    SALMON    RIVER,   IDAHO. 

Many  local  glaciers  originated  in  the  Bitterroot  Mountains  and  flowed 
down  into  the  valleys  of  the  Salmon  River  and  its  tributaries.  The  Lemhi 
Valley  for  many  miles  above  Salmon  City  is  several  miles  wide.  It  is  a 
valley  of  erosion  in  sedimentary  fresh- water  lake  beds.  In  the  bottom  of 
the  valley  is  an  extensive  plain  of  rounded  gravel  and  cobbles,  while  on  the 
tops  of  mesas  200  to  300  feet  higher  is  a  thin  sheet  of  similar  material. 
This  higher  gravel  may  be  due  to  a  more  ancient  glaciation  than  the  last, 
or  it  mav  have  been  formed  on  the  margin  of  a  great  confluent  glacier  that 
filled  the  whole  valley.  It  is  probable  that  some  or  all  of  these  are  beach 
pebbles  of  the  old  lake. 

West  of  Salmon  City  lies  the  Salmon  River  Range  of  mountains. 
They  rise  rather  steeply  from  the  valleys  of  Salmon  River  and  its  trib- 
utaries up  to  an  altitude  of  6,000  to  9,000  feet.  The  main  range  lies  neai-ly 
north  and  south,  and  there  are  several  spm-s  reaching  out  to  the  west  and 
northwest.  The  rocks  are  very  ancient  quartzites,  slates,  and  schists  with 
intervening  and  bordering  areas  of  coarser  granites  and  a  few  extrusions  of 
rather  recent  acidic  volcanic  rocks.  The  original  masses  of  upheaval  have 
been  dissected  into  many  valleys  and  basins,  and  show  plainly  the  marks 
of  geological  old  age.  The  mountains  are  well  exposed  to  moist  winds 
from  the  Pacific  Ocean,  and  the  precipitation  is  large. 

Napius  Creek  drains  a  large  area  on  the  western  slopes  of  these 
mountains  and  flows  into  Big  Creek,  itself  a  tributary  of  Salmon  River.  I 
have  had  opportunity  to  partially  explore  the  upper  20  miles  of  this  valley, 
extending  7  miles  west  from  the  old  mining  camp  of  Leesburg  to  the 
so-called  Falls  of  Napius  Creek.  Here  the  stream  cuts  through  a  high 
ridge  of  granite,  and  thence  descends  by  a  series  of  rapids  and  cascades  to 


352  GLACIAL  GEAVELS  OF  MAINE. 

Big  Creek.  Numerous  lateral  valleys  extend  from  the  main  creek  from  5 
to  10  miles  into  the  mountains.  The  area  of  this  part  of  the  valley  is 
^boiit  300  square  miles.  The  elevation  of  the  Falls  of  Napius  (or  Bull  of 
the  Woods)  is  about  5,700  feet.  Lying  east  of  this  point  is  an  area  of 
several  square  miles  of  volcanic  rock,  then  a  crescent  of  schists  and  quartz- 
ites,  and  around  that  a  crooked  belt  of  granites.  This  makes  it  easy  to  dis- 
tinguish local  from  transported  matter. 

The  lateral  valleys  and  cirques  were  once  filled  by  glaciers  which 
united  in  the  main  valley  to  form  a  large  glacier  or  ice-sheet  that  rose 
above  the  hills  adjoining  the  main  creek  so  as  to  extend  back  for  a  mile  or 
more  into  the  lateral  valleys.     This  is  proved  by  the  following  facts: 

The  quartzites  resist  chemical  decay,  but  readily  fracture.  The 
volcanic  rocks,  granites,  and  schists  yield  to  both  fracture  and  chemical 
action.  Hence  the  exposed  rock  has  seldom  preserved  its  glacial  scratches. 
Presh  exposures  reveal  glaciated  rock  in  various  2jlaces  in  the  valley. 

MORAINES. 

Moraines  of  four  kinds  were  observed. 

Lateral  moraines. — Tlic  slopcs  of  tlic  Mlls  uext  to  tlic  maiu  vallcys  are 
strewn  with  a  scattering  of  erratic  material,  but  no  distinct  or  prominent 
ridges  or  terraces  were  found. 

Terminal  moraines. — About  2  mllcs  east  of  tho  Falls  of  Naplus  is  a  moraine 
on  the  north  side  of  the  creek  beginning  near  the  stream  and  extending  at 
nearly  a  right  angle  to  the  creek  northward  up  to  an  elevation  of  about  800 
feet  above  the  creek.  It  forms  a  series  of  low  ridges  with  some  outlying 
spurs.  The  mountainside  on  which  it  lies  rises  pretty  steeply  from  the 
stream.  The  great  depth  of  the  ice  at  this  point  makes  it  certain  that  the 
glacier  extended  far  beyond  the  region  explored;  hence  this  is  a  retreatal 
moraine.  The  moraine  corresponding  to  this  on  the  south  side  of  the  creek 
has  disappeared  near  the  stream  on  a  very  steep  slojoe.  There  are  several 
other  small  terminal  or  retreatal  moraines  above  this  at  intervals  in  the 
valley. 

Crag  and  tail. — Tlic  high  granite  ridge  which  extends  northeastward  from 
the  Falls  of  Napius  shows  no  erratics  till  we  reach  a  point  three-fourths  of  a 
mile  north  from  the  creek.  Here  on  a  broader  part  of  the  ridge  is  a  moraine 
•consisting'  of  well-g'laciated  stones  with  a  few  bowlders.     It  forms  a  sheet 


VALLEY  OF  SALMON  EIVEE.  353 

that  caps  the  ridge  and  is  only  200  or  300  feet  wide  and  a  short  fourth  of  a 
mile  long.  It  formed  in  lee  of  a  small  peak  of  volcanic  rock  that  projects 
about  30  feet  above  the  side  of  the  little  peak,  and  a  few  glaciated  stones 
are  also  found  on  the  other  two  sides  of  the  crag,  but  none  on  its  top. 
Perhaps  a  better  name  for  this  arrangement  would  be  "crag  and  collar." 
This  is  about  500  feet  above  Napius  Creek. 

Crag  and  cap. — About  3  milcs  cast  of  the  last-named  localit}^  and  1  mile 
south  of  Napius  Creek  is  an  oblong-conical  hill  rising  about  800  feet  above 
the  creek.  The  top  of  the  hill  is  capped  by  a  ridge  of  glaciated  matter  and 
erratics.  The  local  rock  is  a  dark  schist  entirely  unlike  the  morainal  mat- 
ter. The  ridge  is  hardly  one-eighth  of  a  mile  long  and  250  feet  wide,  with 
steep  lateral  slopes.  It  contains  many  granite  bowlders  from  10  up  to  20 
feet  in  diameter. 

I  noticed  several  other  moraines  capping  hills  at  diiferent  elevations. 
These  moraines  are  separated  by  large  areas  that  show  little  or  no  foreign 
matter.  We  have  not  a  sheet  of  till,  like  that  which  covers  New  England, 
but  local  masses  here  and  there.  The  situations  of  these  high  moraines 
described  as  crag  and  collar  and  crag  and  cap  appear  to  be  similar  to  the 
moraines  now  forming  at  the  nunatakker  of  the  Greenland  ice-sheet.  They 
probably  formed  when  the  hills  rose  near  or  above  the  surface  of  the  ice. 
It  is  doubtful  whether  this  drift  was  transported  subglacially  or  supergla- 
cially,  or  both.  The  large  areas  bare  of  transported  matter  favor  the 
hypothesis  of  much  of  sui-face  transportation;  the  intense  glaciation  of 
much  of  the  morainal  matter  favors  the  subglacial  hypothesis. 

GLACIAL    GKAVELS. 

One  of  the  most  noticeable  features  of  this  valley  is  the  large  sheet  of 
waterworn  gravel,  cobbles,  and  bowlderets,  with  some  bowlders,  which  once 
filled  the  bottom  of  the  main  valley  and  thence  extended  up  the  lateral  val- 
leys for  several  miles.  The  stream  has  eroded  the  old  plain  to  depths  of  30 
to  70  feet,  the  uneroded  portions  forming  terraces,  known  to  placer  miners 
as  bars.  As  we  go  back  from  the  stream  the  gravel  slopes  upward  100  or 
more  feet  per  mile.  Excavations  for  placer  mining  show  that  under  the 
gravel  lies  well-glaciated  rock  in  place.  The  gravel  plain  is  2  miles  wide 
a  short  distance  west  from  Leesburg.  Mixed  with  much  waterworn  matter 
are  some  stones  bearing  glacial  scratches.     The  proportion  of  this  sort  of 

MON  XXXIV 23 


354  GLACIAL  GRAVELS  OF  MAINE, 

stones  increases  as  we  go  back  from  the  main  creek.  Some  of  these  enlarge- 
ments of  the  gravel  plain  maj  have  been  deposited  in  glacial  lakes  caused 
by  some  of  the  lateral  glaciers  flowing  across  the  main  valley  and  damming 
it.  I  nowhere  found,  however,  anything  that  resembles  the  reticulated 
kames,  though  there  are  here,  as  in  numerous  places  in  the  Arkansas  Val- 
ley, low  swells  or  ridges  obliquely  transverse  to  the  course  of  the  glaciers 
showing  one  slope  of  the  cross  section  shorter  and  steeper  than  the  other. 
In  all  cases  the  distal  slope  is  the  steeper.  A  large  amount  of  water-rounded 
matter  is  found  in  the  valleys  below  the  region  visited. 

SUMMARY. 

An  ice-sheet  covered  the  bottom  of  the  valley  of  Napitis  Creek  and 
rose  above  the  hills  near  the  river.  Higher  in  the  mountains  the  hills  sepa- 
rating the  lateral  valleys  probably  rose  above  the  snow ;  they  certainly  rose 
far  above  the  confluent  glacier  of  the  main  valley.  This  ice-sheet  formed 
^'nunatak"  moraines  at  various  points,  but  no  continuous  sheet  of  till.  The 
proportion  of  water-rolled  as  compared  with  morainal  matter  is  very  large. 
This  seems  to  indicate  that  this  gravel  plain  was  formed  in  front. of  the  ice 
during  the  final  melting-.  The  much-rolled  matter  was  poured  out  by  the 
subglacial  streams  in  front  of  the  ice,  and  the  morainal  matter  that  was  on 
or  in  the  ice  fell  into  the  water  at  the  ice  front,  and  thus  received  too  little 
waterwear  to  efface  the  glacial  scratches.  The  gravels  poured  out  during 
the  time  of  maximum  depth  of  ice  are  beyond  the  field  explored. 

GENERAL    SUMMARY    OF    THE    ROCKY   MOUNTAIN    REGION. 

The  above-recorded  observations  cover  nearh'  10  degrees  of  latitude, 
though  most  of  them  were  made  in  the  State  of  Colorado. 

Several  characteristics  of  the  glaciation  of  the  mountain  region  deserve 
attention. 

1.  All  writers  are  agreed  that  the  mountain  glaciers  were  confined  to 
single  drainage  basins.  We  find  the  nearest  approach  to  ice-sheets  in  the 
larger  valleys,  where  the  tributaries  united  to  form  glaciers  that  rose  above 
the  low  hills  and  ridges  nearest  the  main  ^'alleys. 

2.  In  general  the  moraines  formed  at  the  ends  or  margins  of  the 
glaciers,  not  subglacially,  with  a  residue  of  cases  where  the  interpretation 
is  doubtful. 


GLACIERS  OF  ALASKA.  355 

3.  All  the  larger  glaciers  formed  extensive  overwash  aprons  or  sheets 
of  water-rolled  material,  which  are  coarser  in  composition  at  the  principal 
terminal  moraines  and  become  tiner  as  we  go  down  the  valleys  below  them. 
This  glacial  gravel  was  deposited  in  diminishing  quantities  as  we  go 
upward  from  the  outer  terminal  moraines.  The  retreatal  terminal  moraines 
extend  higher  up  the  valleys  than  the  water-rolled  matter,  and  often  we 
find  above  the  last  gravel  deposit  a  number  of  retreatal  moraines  scattered 
over  a  space  of  a  mile  or  two.  Almost  every  valley  in  the  mountains 
attests  that  the  small  glaciers  that  marked  the  final  disappearance  of  the 
ice  formed  but  little  glacial  sediment,  and  what  there  is  shows  only  a  lim- 
ited amount  of  waterwear. 

4.  The  glacial  gravel  is  deposited  in  rather  level  or  even  plains  or 
terraces,  sometimes  rising  one  above  another  as  we  go  back  into  the  moun- 
tains. No  ordinary  kames  or  osars  are  found,  though  the  low  ridges 
transverse  to  the  course  of  the  glacier  above  noted  are  in  some  degree  a 
correlative  deposit  to  the  retreatal  moraines  and  "kames"  observed  by 
Wright  near  the  Muir  glacier.  They  are  an  eighth  of  a  mile  broad,  and 
the  interpretation  is  doubtful.  They  are  well  developed  in  a  small  valley 
3  miles  north  of  Twin  Lakes  in  the  Arkansas  Valley.  In  several  places, 
such,  for  instance,  as  the  valle}^  of  the  Arkansas  12  miles  south  of  Lead- 
ville,  on  the  east  side  of  the  river,  there  is  a  jumble  of  heaps  and  ridges  of 
glacial  gravel,  but  this  is  due  to  unequal  erosion  of  a  once  continuous  sheet. 

The  sheets  of  glacial  gravel  of  the  Rocky  Mountain  glaciers  are  rather 
horizontally  stratified  and  in  their  surface  features  resemble  the  broad  osars 
or  osar  terraces  of  Maine.  They  are  the  equivalents  of  the  deposits  I  have 
termed  "frontal  deltas"  in  Maine.  But  whereas  in  the  mountains  the  finer 
clay  and  sand  was  at  once  swept  away  by  the  rapid  streams,  except  locally 
in  glacial  lakes,  in  Maine  the  slopes  were  so  gentle  that  they  form  broad 
sheets  of  silts  and  clays  widely  covering  the  valleys  all  the  way  to  the  sea- 
shore of  that  time. 

GLACIERS  OF  ALASKA. 

The  origin  of  frontal  or  overwash  aprons  of  glacial  gravel,  also  of 
kames  such  as  are  formed  by  valley  glaciers,  is  illustrated  by  the  Mount 
St.  Elias  glaciers  described  by  Prof.  Israel  C.  Russell.^     The   Malaspina 


'  Nat.  Geog.  Mag.,  vol.  3,  pp.  53-204;  also  Am.  Jonr.  Sci.,  Sfl  series,  vol.43,  pp.  169-182,  March,  1892. 


356  GLACIAL  GRAVELS  OF  MAINE. 

glacier  ajDproaches  the  character  of  a  local  ice-sheet,  and  more  nearly  illus- 
trates the  conditions  of  the  ice-sheet  in  Maine  than  of  ordinary  Alpine  or 
valley  glaciers.  Over  large  areas  it  is  nearly  stagnant.  During  the  decay 
of  the  ice-sheet  in  Maine  there  must  have  been  many  places  where  the  ice 
was  in  nearly  the  same  condition,  the  forward  flow  being  arrested  by  high 
transverse  hills  in  front,  while  often  the  supply  from  the  n^ve  was  also 
obstructed  by  still  higher  hills  10  to  30  miles  farther  north. 

Some  of  the  formations  illustrated  by  the  observations  of  Professor 
Russell  are  the  following: 

OVEKWASH   APRONS. 

Along  the  south  era  margin  of  the  Malaspina  glacier,  between  the  Yahtse  and 
Point  Manby,  there  are  hundreds  of  streams  which  pour  out  of  the  escarpment  formed 
by  the  border  of  the  glacier  or  rise  like  great  fountains  from  the  gravel  and  bowlders 
at  its  base.  All  of  these  streams  are  bi-own  and  heavy  with  sediment  and  overloaded 
with  bowlders  and  stones.  *  *  *  Tlie  most  interesting  of  these  is  Fountain  Stream. 
This  comes  to  the  surface  in  one  great  spring  fully  100  feet  across.  The  water  I'ises 
nnder  such  pressure  that  it  is  thrown  12  or  15  feet  into  the  air,  and  sends  up  jets  of 
spray  6  or  8  feet  higher.  It  then  rolls  seaward,  forming  a  broad,  swift  river  which 
divides  and  spreads  out  in  many  channels  both  to  the  right  and  left  and  has  inundated 
several  hundred  acres  of  forest  land  with  gravel  and  sand.' 

This  admirably  illustrates  the  formation  of  the  large  sheets  of  over- 
wash  gravels  that  extend  outward  from  the  terminal  moraines  of  the  iipper 
Arkansas  Vallej^  and  many  other  valleys  in  the  mountain  region.  In 
Maine  we  have  a  nearly  correlative  deposit  in  the  plain  of  coarse  gravel 
that  extends  across  the  Carrabassett  Valle}'  near  East  New  Portland  and 
North  New  Portland,  and  in  several  other  valleys,  as  elsewhere  described, 
especially  in  the  valley  of  the  Androscoggin  River  in  Bethel  and  Gilead, 
Maine,  and  extending-  into  Shelburne  and  Gorham,  New  Hampshire. 

OSAK  STREAMS  AND  OSARS. 

The  principal  streams  on  the  eastern  margin  in  1891  were  the  Osar,  Kame,  and 
Kwik.  Each  of  these  issues  from  a  tunnel  and  then  flows  for  some  distance  between 
walls  of  ice.  Of  the  three  streams  mentioned  the  most  interesting  is  the  Kame. 
This  issues  from  the  mouth  of  a  tunnel  in  the  ice  about  3  miles  back  from  the 
actual  border  of  the  glacier,  and  flows  for  half  a  mile  in  a  narrow  canyon  with  walls 
of  dirty  ice  50  feet  or  more  high.  The  canyon  then  expands  and  forms  a  valley 
bordered  by  moraine-covered  hills  of  ice,  which  gradually  widens  toward  the  east 
until  it  merges  with  a  low  marshy  tract  bordering  the  shore  of  the  bay.     Well-rounded 


'  Am.  Jonr.  Sci.,  3d  series,  vol.  43,  p.  179,  March,  1892. 


OSAE  STREAMS  AND  OSAES  IN  ALASKA.  357 

sand  and  gravel  is  being  deposited  by  this  stream  in  large  quantities.  This  covers 
the  ice  over  which  the  stream  flows,  and  during  former  stages  was  deposited  in 
terraces  along  the  lower  portion  of  the  channel.  These  terraces,  in  part,  at  least,  rest 
on  ice.  The  rounded  and  worn  condition  of  the  gravel  and  sand  brought  out  of  the 
tunnel  is  proof  that  it  has  had  a  long  interglacial  or  subglacial  journey. 

On  the  north  side  of  the  open  channel  of  Kame  Stream  there  is  a  sharp  ridge  of 
well-rounded  gravel  which  runs  parallel  with  the  present  river,  and  in  places  can  be 
seen  to  rest  on  an  icy  bed.  This  was  evidently  deposited  by  a  stream  similar  to  the 
present  one,  but  which  flowed  fully  100  feet  higher.  This  ridge  of  gravel  seems  to 
be  of  the  same  general  character  as  the  kames  of  New  England  and  other  glaciated 
regions.  *  *  *  The  formation  of  osars  seems  fully  explained  by  the  subglacial 
drainage  of  the  Malaspina  ice-sheet.^ 

In  two  important  conditions  the  Malaspina  ice-slieet  or  Piedmont 
glacier  varies  from  the  ice-sheet  of  Maine.  1.  In  Maine  the  morainal 
matter  was  basal,  i.  e.,  contained  in  the  lower  part  of  the  ice  and  taken 
into  the  ice  from  below,  while  the  drift  of  the  Malaspina  glacier  is  on  its 
surface  (marginal)  or  scattered  through  it  to  a  great  height — the  result 
of  avalanches  bringing  down  fragments  of  rock  and  depositing  them  in 
successive  layers  on  the  n4v4s  of  the  glaciers.  2.  The  Mount  St.  Elias 
glaciers  are  bordered  by  considerable  land  bare  of  ice,  and  a  large  amount 
of  water  warmed  above  32°  flows  onto  the  glaciers  and  helps  to  form  and 
enlarge  the  subglacial  channels.  The  amount  of  heat  thus  transferred  to 
points  beneath  the  ice  is  very  much  greater  than  that  carried  by  superficial 
waters  of  the  ice  surface  pouring  down  crevasses.  In  Maine  the  hills  are 
so  low  that  in  only  a  few  of  the  most  mountainous  regions  would  the  con- 
ditions at  all  approach  those  of  Alaska.  Over  most  of  the  State  the  glacier 
would  be  reduced  to  only  200  or  500  feet  in  thickness  before  any  of  the 
land  would  rise  above  the  surface  of  the  ice.  In  the  upper  Kennebec 
Vallej^  there  are  a  few  high  gravel  terraces  that  may  have  been  formed  by 
streams  flowing  in  the  depression  that  forms  at  the  margin  of  a  glacier  next 
a  mountainside,  but  such  gravels  are  rare.  I  have  nowhere  yet  found  in 
Maine  the  delta  terraces  of  such  marginal  lakes  as  Professor  Russell  finds 
so  abundantly  in  Alaska.  The  short  hillside  osars  were  formed  by  streams 
that  flowed  down  steep  southern  slopes.  They  often  expand  into  deltas  at 
the  bottoms  of  the  hills,  but  there  is  no  series  of  terraces  marking  successive 
levels  of  the  water,  except  iu  the  courses  of  the  great  osar  rivers.  These 
were  fed  by  glacial  waters,  not  by  waters  of  the  land  bare  of  ice. 

'  Am.  Jour.  Sci.,  3d  series,  vol.  43,  p.  180. 


358  GLACIAL  GRAVELS  OF  MAINE. 

It  should  also  be  noted  that  the  extreme  stagnation  of  the  Malaspina 
glacier  must  favor  the  solidification  of  the  lower  rce  and  the  other  causes, 
whatever  they  are,  for  the  subglacial  streams  rising  onto  the  surface  of  the 
ice.  In  cases  of  rapid  glaciers  flowing  into  the  sea  the  subglacial  streams 
are  discharged  into  the  sea  and  do  not  rise  to  the  surface  of  the  ice  some 
miles  back  from  the  seas,  as  is  the  case  of  this  interesting  glacier. 

The  ridge  described  above  as  found  on  the  ice  would  probably  lose  its 
stratification  during  the  melting  of  the  subjacent  ice  and  in  structure 
resemble  Indian  Ridge  at  Andover,  Massachusetts,  rather  than  the  ordinary 
stratified  osar. 


CHAPTERVI. 
CLASSIFICATION  OF  THE  GLACIAL  SEDIMENTS  OF  MAINE. 

PRELIMINARY    RE1HARK8. 

NAMES. 

A  complete  classification  of  the  glacial  sediments  will  not  be  possible 
till  the  facts  of  all  the  glaciated  countries  are  correlated.  The  masses  of 
glacial  gravel  have  everywhere  received  local  names,  the  ones  in  most 
common  use  by  geologists  being  the  Scotch  name  kame,  the  Irish  esker,  and 
the  Swedish  osar.  At  first  geologists  employed  these  terms  as  promiscu- 
ously as  they  are  employed  in  popular  usage.  Later  an  attempt  has  been 
made  at  a  classification  founded  on  genesis.  In  a  recent  letter  Professor 
Chamberlin  has  set  forth  his  views  on  this  subject  as  follows: 

When  these  gravel  accumulations  arranged  themselves  in  transverse  irregular 
belts  and  represent  marginal  action,  especially  where  associated  with  thrusting  action 
on  the  part  of  the  ice,  they  should  be  distinguished  from  the  longitudinal  gravel 
ridges  which  represent  the  internal  drainage  system  of  the  ice  and  whose  develoi»ment 
is  quite  largely  dependent  on  a  stagnant  or  slow-moving  condition  of  the  ice  in  its  last 
stages. 

With  the  first  class  is  associated  the  name  "kame,"  with  the  second  the 
name  "osar." 

As  between  the  terms  "osar"  and  "esker,"  the  first,  as  I  understand  it, 
has  right  of  priority.  The  finest  known  example  of  the  longer  gravel  ridges 
is  found  in  Sweden,  the  next  is  that  of  Maine.  According  to  published 
descriptions  the  gravels  of  Maine  are  more  like  those  of  Sweden  than  of 
Ireland.  Certainly  the  grandest  gravel  system  of  all  ought  to  receive 
recognition  in  our  nomenclature.  I  retain  the  term  "osar"  for  the  longitu- 
dinal gravel  system,  and  shall  for  the  present  employ  the  word  "esker"  as  a 
general  term  applicable  to  any  mass  or  ridge  of  glacial  gravel  irrespective 
of  genetic  classification.     Thus,  if  a  series  of  separated  deposits  be  known 

359 


360  GLACIAL  GRAVELS  OP  MAINE. 

as  a  discontinuous  osar,  we  need  some  terni  to  apply  to  the  separate 
mounds  and  ridges,  and  for  such  purposes  I  employ  the  word  "esker." 

The  gravel  masses  have  various  external  features,  such  as  continuity 
or  discontinuity,  narrowness  of  ridge  with  arched  cross  section  or  breadth 
with  horizontal  cross  section,  reticulations,  etc.,  which  have  to  be  described 
by  the  use  of  various  modifying  terms. 

It  is  often  a  doubtful  question  how  far  local  usages  of  language  ought 
to  be  followed  by  geologists.  For  instance,  the  word  "plain"  is  in  very 
common  use  in  Maine  to  denote  rather  level  or  gently  rolling  tracts  of  gla- 
cial gravel  and  sands,  generally  with  some  definitive,  such  as  "Norway 
plains"  (meaning  tracts  of  reticulated  kames  overgrown  with  yellow  or 
"Norway  pines"),  " checkerberry  plains,"  "blueberry  plains,"  "Litchfield 
Plain."  In  all  these  cases  popular  usage  has  recognized  that  these  "plains" 
are  tracts  of  sand  or  gravel  diftering  in  composition  from  the  soils  of  the 
surrounding  regions;  and  since  they  are  much  more  level  than  the  hills, 
they  come  to  be  known  as  "plains,"  even  though  the}^  as  little  deserve  the 
title  "plains"  as  do  the  Great  Plains  west  of  the  Missouri  Eiver.  It  is 
doubtful  if  geologists  can  go  to  Maine  and  inquire  their  way  to  msiuj  of 
the  localities  and  deposits  described  in  this  report  without  employing  the 
word  "plains"  in  their  inquiries.  While  it  may  be  conceded  that  in  strict 
geological  language  it  is  desirable  to  use  the  word  "plain"  only  where  it 
has  a  natural  geometrical  application,  yet  there  are  disadvantages  in  cutting 
entirely  loose  from  local  usage. 

On  reflection,  instead  of  the  term  "osar-plain"  for  the  broad  osar,  the 
term  "osar  terrace"  will  often  be  used,  partly  because  the  term  "moraine 
terrace"  was  used  many  years  ago  by  Prof.  C.  H.  Hitchcock^  to  distinguish 
reticulated  masses  of  glacial  gravel. 

GLACIAL    GRAVELS    AS    MODIFIED    BY    THE    SEA. 

I  assume  that  all  the  outer  coast  of  Maine  below  the  contour  of  225 
feet,  pei-haps  below  that  of  230  feet,  was  under  the  sea  during  the  last  part 
of  the  Glacial  period.  In  the  interior  of  the  State  the  sea  must  have  stood 
at  a  somewhat  greater  height  in  the  principal  river  valleys,  then  deep  bays. 

In  general  the  glacial  gravels  that  were  under  the  sea  at  any  time  are 
somewhat  different  in  external  form  from  those  situated  above  the  former 

I  Preliminary  Keport  upon  the  Natural  History  and  Geology  of  the  State  of  Maine,  p.  270, 1861. 


SHORT  ISOLATED  OSAES  OR  ESKEES.  361 

sea  level.  The  lenticular  and  broadly  arched  types  prevail.  The  lateral 
slopes  are  usually  quite  gentle.  In  many  cases  the  waves  washed  over  the 
tops  of  the  kames  and  osars,  eroding  a  portion  of  the  upper  parts  of  the 
ridges  and  molding  their  external  forms  near  to  that  of  the  sand  bar  of  the 
coast.  For  some  time  I  supposed  that  all  the  gravels  that  had  been  beneath 
the  ocean  had  been  thus  acted  upon.  Later  I  have  discovered  mounds 
showing  the  same  features  in  valleys  that  were  occupied  by  long  narrow 
straits  and  inlets,  yet  so  2Drotected  from  marine  erosion  that  their  change 
in  form  from  this  cause  must  have  been  small.  Thus  the  north-and-south 
valley  of  Georges  River  was  at  one  time  a  strait  extending  from  the  Bel- 
fast Bay  of  that  period.  For  10  or  more  miles  it  was  only  from  one-fourth 
mile  to  near  a  mile  wide.  On  the  east  were  the  high  hills  of  Hope,  Cam- 
den, and  Lincolnville,  and  a  high  ridge  lay  on  the  west.  The  strait  Avas 
well  landlocked  and  protected  from  the  outside  waves.  The  gravel  cones, 
domes,  and  short  ridges  of  this  valley  are  more  or  less  covered  by  marine 
clay  and  have  the  same  outline  that  is  common  elsewhere  in  the  region  that 
was  under  the  sea,  and  there  are  no  gravels  washed  down  upon  the  adjacent 
clays.  The  same  is  true  of  the  discontinuous  system  in  the  Medomac  Val- 
ley above  Waldoboro.  While,  then,  it  is  certain  that  in  exposed  situations, 
as  on  the  tops  of  the  hills  at  Portland,  the  tops  of  the  gravels  were  more  or 
less  eroded  and  molded  by  the  sea,  yet  we  must  conclude  that  in  addition 
to  this  effect  there  was  a  difference  in  the  average  forms  of  deposition  ot 
the  gravels  of  the  coast  and  those  of  the  interior.  The  former  are  less 
steep  and  ajjproach  the  flowing  outlines  of  the  drumlins. 

Divided  into  classes  according  to  their  external  features,  the  glacial 
sediments  are  as  follows: 

SHORT  ISOIiATED  OSAES  OR  ESKERS. 

These  are  perhaps  the  simplest  form  of  the  glacial  gravels.  The  term 
"isolated"  is  applied  to  them  because  no  other  gravels  are  known  to  be  near 
them  in  such  relations  that  their  formation  can  be  attributed  to  the  same 
glacial  stream.  They  have  the  form  of  a  cone,  a  dome,  or  often  a  short 
ridge,  or  sometimes  several  short  ridges  having  a  linear  arrangement  (length- 
wise of  the  ridges),  or  occasionally  a  few  somewhat  parallel  ridges  inclosing 
basins.  They  vary  in  length  from  a  few  feet  up  to  a  mile  or  two.  A  dis- 
tinguishing feature  of  the  class  is  that  they  have  no  fan-shaped  or  enlarged 


362  GLACIAL  GEAVELS  OF  MAINE. 

delta  showing  assortment  of  material  from  coarse  on  one  side  (next  the 
ridge)  to  very  tine  on  the  other,  the  stratification  also  becoming  more  and 
more  horizontal.  Yet  the  material  of  the  ridges  often  shows  some  horizontal 
gradation,  the  finer  sediment  being  situated  at  the  south.  The  assortment 
is  not  so  complete  when  the  deposit  consists  of  ridges  as  where  it  expands 
into  a  broad,  flat  plain.  Near  the  coast  the  isolated  eskers  mostly  take  the 
form  of  cones,  domes,  or  short  lenticular  ridges.  In  the  interior  they  are 
almost  always  short  ridges,  which  the  lumbermen  report  as  "horsebacks." 
North  of  the  region  of  the  long  osars  they  are  the  only  form  of  glacial 
gravel  reported  by  the  State  geologists  of  Maine  or  others,  or  discovered 
by  me.  Thus  I  have  note  of  quite  a  number  of  short  ridges  in  the  valley 
of  the  Masardis  or  St.  Croix  River,  which  flows  north  into  the  Aroostook 
River.  It  is  possible  that  these  are  part  of  a  connected  series,  but  I  can  not 
prove  it.  Lumbermen  report  great  numbers  of  horsebacks  in  the  region 
drained  by  the  St.  John  River,  but  many  of  these  are  elongated  drumlins — 
at  least  farther  south  I  have  found  many  of  the  horsebacks  to  be  such. 

What  were  the  conditions  under  which  the  isolated  osars  or  eskers  were 
formed?  A  good  type  is  found  about  a  mile  south  of  New  Vineyard  Post- 
Office.  The  esker  is  situated  in  the  jaws  of  a  north-and-south  pass  through 
the  high  hills.  It  is  about  10  feet  high  and  150  feet  long.  In  the  pass 
is  a  divide  where  the  drainage  Avaters  part,  some  flowing  north  toward 
New  Portland,  others  south  to  Farmington.  The  ridge  is  situated  on  the 
northern  slope  about  one-fourth  of  a  mile  north  of  the  divide.  There  is  a 
considerable  amount  of  alluvium  south  of  this  divide  all  the  way  to  Farm- 
ington, and  it  is  probable  that  it  is  some  form  of  glacial  sediments  or  frontal 
matter,  but  this  I  have  not  proved.  To  the  north  of  the  esker  broad  open 
valleys  extend  all  the  way  to  Kingfield  and  Mount  Bigelow.  In  late  glacial 
time  the  ice  would  naturally  linger  in  these  valleys  after  the  ice  south  of 
the  divide  was  all  melted,  since  a  supply  could  readily  come  from  the 
region  of  high  hills  near  the  Dead  River.  After  the  front  of  this  tongue  of 
ice  had  retreated  north  of  the  divide  a  small  lake  would  be  formed  south 
of  the  ice,  confined  between  the  ice  and  the  hill  or  divide  lying  south  of  it. 
The  slopes  are  gentle,  and  this  lake  would  not  be  more  than  15  or  perhaps 
20  feet  deep  at  the  time  when  the  extremity  of  the  ice  had  receded  as  far 
north  as  the  position  of  the  ridge.  The  lake  would  nowhere  be  more  than 
one-eighth  of  a  mile  wide.     If  a  glacial  stream  poured  into  the  supposed  lake. 


SHORT  ISOLATED  OSAES  OE  ESKEES.  363 

it  would  spread  out  its  sediments  to  form  a  delta.  There  is  some  fine 
alluvium  in  the  valley,  but  it  is  not  in  the  form  of  an  expansion  of  the 
esker.  The  place  is  so  near  the  top  of  the  divide  that  there  has  been  but 
little  erosion.  The  fact  that  we  find  a  gravel  ridge  without  a  delta  in  a  place 
so  favorable  to  the  formation  of  a  delta  indicates  that  the  ridge  was  deposited 
within  the  ice  walls  before  the  ice  had  receded  as  far  north  as  the  esker,  and 
before  the  formation  of  the  lake,  in  which  probably  at  a  later  period  was 
deposited  the  fine  alluvium  of  the  valley  near  the  kame. 

At  one  of  the  small  isolated  eskers  we  have  distinct  evidence  of  a 
glacial  stream  for  a  short  distance.  Several  questions  naturally  arise  as  to 
whence  the  waters  came  and  whither  they  went,  as  to  the  work  they  had 
done  before  coming  to  the  place  of  the  esker,  and  what  became  of  the  finer 
mud  and  clay  which  they  must  have  carried  away  with  them.  There  are 
several  alternative  hypotheses. 

1.  A  sediment-laden  superficial  stream  hei'e  plunged  down  a  crevasse. 
The  coarser  sediment  was  deposited  in  the  enlargement,  cave,  or  pool  within 
the  ice  that  naturally  formed  near  the  base  of  the  waterfall.  The  water  then 
escaped  through  a  subglacial  tunnel,  carrying  the  finer  matter  with  it. 

2.  The  esker  collected  in  an  enlargement  or  pool  in  the  bottom  of  the 
channel  of  a  superficial  stream.  Such  an  enlargement  may  have  been 
begun  as  a  pothole  or  pool  in  the  ice  at  the  base  of  a  rapid  or  waterfall 
over  ice  or  where  lateral  ti'ibutai'ies  poured  into  the  main  channel. 

3.  The  esker  may  have  been  formed  in  the  tunnel  of  a  subglacial 
stream.  In  such  a  case  we  must  account  for  the  waters  being  checked  for 
a  part  of  the  course  of  the  stream,  while  above  and  below  the  water  flowed 
so  swiftly  that  it  left  little  or  no  sediment  in  its  tunnel,  or  else  we  must 
postulate  some  obstacle  greater  than  elsewhere  to  the  passage  of  the  trans- 
ported matter.  Such  an  obstacle  could  be  furnished  by  the  stream  crossing 
an  up  slope.  We  sometimes  find  isolated  eskers  in  such  positions,  but  also 
often  on  down  slopes  where  change  in  angle  of  bed  can  not  have  checked 
the  sediment.  Such  an  obstacle  might  also  be  formed  by  a  bowlder  or  mass 
of  ice  fallen  from  the  roof  of  the  tunnel. 

The  velocity  of  the  water  could  be  locally  checked  by  an  upward 
slope  of  the  bottom  of  the  channel,  provided  the  tunnel  was  not  full  of 
water,  but,  as  above  noted,  we  often  can  not  invoke  change  of  slope  to 
account  for  local  deposition.     Another  way  for  checking  the  velocity  would 


364  GLACIAL  GRAVELS  OF  MAINE. 

be  by  enlarging  the  channel.  Such  enlargements  must  constantly  be 
forming  where  superficial  streams  bring  warmed  waters  and  pour  them 
down  a  crevasse  into  the  glacial  river. 

Here  are  a  number  of  physical  causes  capable  of  doing  the  required 
work,  and  perhaps  no  two  of  the  kames  were  formed  in  exactly  the 
same  way. 

I  have  many  times  examined  the  country  adjacent  to  the  isolated 
eskers  for  signs  of  glacial  streams  beyond  the  limit  of  the  gravels  them- 
selves. Thus  far  I  have  found  no  ravine  of  erosion  in  the  till  or  glacial 
potholes,  either  north  or  south  of  these  eskers.  They  begin  and  end 
abruptly,  and  beyond  them  we  pass  into  regions  covered  by  ordinary  till. 
But  it  may  fairly  be  urged  that  the  channels  of  subglacial  streams,  being 
underneath  the  ice,  are  now  covered  by  the  upper  or  englacial  till,  while  in 
the  region  that  was  beneath  the  sea  we  have  the  search  further  embarrassed 
by  the  deep  sheets  of  marine  clays  which  cover  almost  all  that  part  of  the 
State.  Indeed,  it  would  be  possible  for  a  ridge  to  end  in  a  fan-shaped  delta 
and  yet  be  so  covered  by  the  clay  that  only  the  top  of  the  highest  part  of 
the  ridge  appeared. 

The  problem  of  the  short  isolated  osars  in  the  region  that  was  under 
the  sea  is  so  nearly  related  to  that  of  the  discontinuous  osars  that  it  will  be 
further  discussed  in  connection  with  that  class  of  gravels.  Above  the 
former  level  of  the  sea,  and  especially  in  the  northern  part  of  the  State, 
the  first  and  third  of  the  above-mentioned  hypotheses  appear  to  me  to  be 
more  probable  than  the  second.  Yet  where  the  material  is  quite  fine  the 
second  method  may  also  have  been  employed.  It  is  not  necessary  to 
premise  that  all  the  eskers  were  formed  in  the  same  manner. 

These  eskers  are  situated  where  no  ordinary  stream  of  land  drainage 
could  have  deposited  them.  There  is  no  way  of  accounting  for  them 
except  that  they  were  deposited  between  solid  walls  that  have  now  disap- 
peared, and  ice  is  the  only  admissible  solid  with  that  property.  The  ice- 
berg theory  of  the  drift  has  no  adequate  explanation  of  them. 

HILLSIDE  OSARS  OR  ESKERS. 

The  only  deposits  of  this  class  of  which  I  have  note  are  found  in  a 
broad  belt  extending  northeastwardly  across  the  State.  Its  southern  bor- 
der lies  about  50  miles  from  the  coast,  and  its  breadth  is  perhaps  75  miles. 


HILLSIDE  OSAES  OR  ESKEES.  365 

The  region  is  hilly.     I  have  noted  about  fifty  of  these  eskers,  and  doubtless 
there  are  many  more. 

At  their  northern  extremities  a  large  proportion  of  the  hillside  systems 
begin  at  the  southern  brow  of  broad  flattish-topped  hills  100  to  400  feet 
hio-h;  others  begin  at  various  distances  down  the  southern  slopes  of  the  hills. 
The  hillsides  fall  southward  or  southeastward.  I  have  discovered  no  ridges 
of  this  class  on  the  northern  slopes  of  hills,  nor  developed  on  the  tops  of 
the  hills  and  plateaus.  These  eskers  all  end  at  the  south  in  the  valleys 
lying  at  the  southern  bases  of  the  hills  in  which  they  are  found.  All  expand 
somewhat  at  their  southern  extremities,  some  into  a  larger  ridge,  some  into 
a  small  plexus  of  reticulated  ridges  inclosing  basins,  some  into  a  fan-shaped 
or  oval  delta.  Beyond  the  limits  of  this  terminal  enlargement  I  have  not 
been  able  to  trace  glacial  sediments,  though  in  some  cases  the  terminal 
deltas  merge  into  the  alluvium  of  the  valleys  in  which  they  lie  in  such  a 
way  as  to  indicate  that  the  alluvium  is  kame  or  overwash  matter  with 
respect  to  the  ice  and  the  glacial  stream.  These  ridges  meander  somewhat, 
yet  on  the  average  diverge  but  little  from  the  lines  of  steepest  slope  of  the 
land  surface.  Owing  to  the  outlook  of  the  hills,  this  direction  is  nearly  the 
same  as  that  of  ice  flow,  and  also  must  be  about  the  same  as  the  direction 
of  the  slope  of  the  ice  surface  in  late  glacial  time.  The  hillside  eskers  vary 
in  height  from  5  feet  or  less  to  20  feet,  and  in  length  from  a  short  eighth  of 
a  mile  to  nearly  2  miles.  The  sediment  composing  them  is  usually  gravel 
and  sand,  but  in  some  cases  there  are  cobbles,  bowlderets,  and  even  a  few 
bowlders,  all  distinctly  but  not  very  much  worn  and  rounded  by  water. 

The  position  of  the  terminal  enlargement  and  delta,  their  situations 
on  the  southern  slopes  of  hills,  and  many  other  considerations  prove  con- 
clusively that  the  flow  of  the  streams  that  deposited  the  hillside  systems 
was  southward.  If  on  the  slopes  of  moderately  steep  hills  the  velocity  of 
the  waters  that  deposited  the  gravels  was  so  gentle  as  to  permit  the 
deposition  of  sediment,  such  as  sand  and  gravel,  we  may  be  certain  that 
the  conditions  would  be  still  more  favorable  to  deposition  on  the  northern 
slopes  and  the  tops  of  the  hills.  On  the  contrary,  no  water  sediments  are 
found  there,  nothing  but  the  usual  till,  and  no  ravines  of  erosion.  If  the 
streams  which  deposited  these  kames  were  subglacial  in  that  part  of  their 
courses  lying  nortn  of  the  kames,  they  there  had  a  very  gentle  current,  not 
capable  of  eroding  the  till  or  transporting  sediments  up  the  hills. 


366  GLACIAL  GRAVELS  OF  MAINE. 

Again,  if  the  hillside  osars  were  diTe  to  local  deposition  in  the  channel 
of  a  long-  north-and-south  glacial  river,  we  ought  to  find  similar  gravels 
forming  a  system  or  connected  series  along  the  course  of  the  hypothetical 
glacial  river.  But  with  a  few  exceptions  the  eskers  of  this  class  can  not  be 
brought  into  any  kind  of  linear  arrangement  with  other  eskers  or  osars. 
In  most  cases  hills  higher  than  200  feet  lie  to  the  south  of  these  eskers, 
sometimes  within  a  mile  or  two,  sometimes  10  or  20  miles  away.  The 
great  rivers  that  have  left  their  gravels  for  a  hundred  miles  could  not  flow 
over  hills  more  than  about  200  feet  high.  No  reason  can  be  assigned  why 
streams  that  have  left  gravels  for  less  than  2  miles  should  be  able  to  flow 
over  any  higher  hills,  or,  if  so,  why  they  have  not  left  gravels  to  mark 
their  channels. 

All  the  facts  point  to  the  conclusion  that  the  hillside  eskers  were 
deposited  very  late  in  the  Ice  period.  They  are  found  in  regions  abounding- 
in  rather  high  hills  lying  transverse  to  the  direction  of  glacial  movement. 
These  hills  stopped  the  motion  as  a  whole  after  the  depth  of  ice  came  to  be 
less  than  about  500  feet,  though  local  movements  would  continue  along 
north-and-south  valleys  like  that  of  the  Kennebec.  So,  too,  there  would  be  a 
limited  flow  from  north  to  south  between  the  successive  ranges  of  transverse 
hills,  especially  on  the  southern  slopes  of  the  hills.  There  would  still  be  a 
surface  gradient  of  the  ice,  since  in  g'eneral  the  melting  was  most  rapid  toward 
the  south  and  the  thickness  of  the  ice  had  originally  increased  northward. 

Some  of  the  hillside  ridges  beg-in  on  the  slopes  of  long  hills  and  have 
1  or  2  miles  of  hill  north  of  them.  In  such  cases  it  is  possible  that  the 
osar  streams  were  wholly  supplied  by  melting  ice  and  other  drainage  of 
the  hill  itself.  But  generally  these  ridges  begin  at  or  near  the  tops  of  the 
southern  slopes  of  the  hills,  where  the  supply  of  local  drainage  would  be 
very  small.  Yet  the  streams  had  considerable  volume  at  the  north,  as,  for 
instance,  the  esker  near  Wilton.  Such  streams  plainly  derived  their  waters 
in  great  part  from  the  regions  lying-  to  the  northward. 

The  best  interpretation  of  the  facts  seems  to  be  as  follows:  The  ice  front 
had  retreated  to  near  the  point  of  the  formation  of  the  streams,  but  the  ice 
north  of  the  hills  was  still  high  enough  to  enable  its  drainage  waters  to  flow 
southward  over  the  hills.  The  absence  of  erosion  channels  or  glacial  sedi- 
ments on  the  tops  and  northern  slopes  of  the  hills  can  be  accounted  for  on 
the  following  suppositions: 

1.  That  superficial  streams  flowed  over  the  hills  from  the  north. 


HILLSIDE  OSAES  OR  ESKEES.  ;  367 

2.  That  subglacial  streams  flowed  up  and  over  the  hills.  North  of  all 
hills  there  is  always  a  portion  of  a  subglacial  stream  tunnel  where  the  water 
is  in  equilibrium  to  the  top  of  the  hill  and  flows  only  as  it  is  urged  by 
water  from  behind  rising  above  the  top  of  the  hill.  If  the  tunnel  were 
rather  large  for  the  supply  of  water,  the  flow  up  the  hill  might  be  so  slow 
that  it  would  not  erode  channels  in  the  ground  moraine  and  the  only  gla- 
cial sediments  would  be  deposited  in  the  valley  to  the  northward.  I  have 
found  no  such  sediments  as  yet.  Or  the  streams  may  have  been  too  small 
to  transport  noticeable  masses  of  gravels. 

Superficial  streams  flowing  from  the  north  might  at  or  near  the  tops 
and  southern  brows  of  the  hills  pour  down  the  crevasses  that  would  natu- 
rally form  there  and  escape  down  the  slopes  as  subglacial  streams,  or  they 
might  continue  in  superficial  channels,  in  which,  after  they  had  cut  down 
to  the  bottom  of  the  ice,  the  gravels  were  deposited.  But  all  observation 
proves  that  on  these  steep  hill  slopes  the  ice  would  almost  certainly  be 
deeply  shattered  by  crevasses,  and  hence  it  is  extremely  unlikely  that  the 
channels  were  superficial  on  the  hillsides.  The  esker  or  kame,  elsewhere 
described  in  Jay,  contains  so  large  bowlderets  and  bowlders  that  it  becomes 
probable  that  this  kame  was  deposited  in  subglacial  vaults.  The  plexus  of 
reticulated  ridges  can  be  accounted  for  on  either  the  theory  of  subglacial 
or  superglacial  streams.  Where  the  terminal  enlargement  takes  the  form 
of  a  horizontally  stratified  delta,  the  stream  evidently  escaped  into  a  pool 
within  the  ice,  or  where  the  delta  spreads  out  in  the  valley  and  passes  by 
degrees  into  the  valley  drift,  the  stream  passed  beyond  the  ice  into  the  open 
valley.  In  this  case  it  is  doubtful  if  the  delta  furnished  the  evidence  neces- 
sary to  decide  definitely  the  question  of  the  nature  of  the  streams. 

The  hillside  eskers  were  perhaps  not  all  deposited  in  the  same  manner. 
They  are  in  situations  so  favorable  to  the  production  of  crevasses  that  it 
would  appear  to  be  inevitable  that  a  part,  if  not  all,  were  formed  by 
streams  which,  no  matter  what  was  their  history  toward  the  north,  escaped 
down  the  hills  as  subglacial  streams.  On  this  hypothesis  the  shortness  of 
the  ridges  would  be  accounted  for  partly  by  the  fact  that  the  water  would 
cease  to  flow  from  the  north  as  soon  as  the  melting  had  progressed  so  that 
the  hills  emerged  from  the  ice.  Some  of  these  kames  seem  to  prove  that 
the  flow  continued  long  enough  to  permit  the  formation  of  subglacial  tun- 
nels in  places  where  there  had  been  none  imtil  the  ice  became  quite 
thin.     These  subglacial  channels  were  not  prolonged  far. 


368  GLACIAL  GEAVELS  OF  MAINE, 

The  formation  of  reticulated  ridges  as  a  part  of  hillside  eskers  will  be 
considered  later. 

These  short  kames  or  eskers  are  not  so  impressive  as  the  long  osars, 
but  they  are  equally  strong  testimony  to  the  existence  of  glacier  ice,  and 
they  possess  the  essential  parts  of  the  longest  osar — a  ridge  and  often  a 
terminal  delta. 

ISOLATED  KAMES  OR  SHORT  ESKERS  ENDING  IK  MARIISHE  DELTAS. 

These  are  confined  to  the  country  lying  below  the  former  level  of  the 
sea.  Litchfield  Plain  is  a  type  of  this  sort  of  deposit.  On  the  north  and 
northwest  are  a  series  of  broad  ridges  somewhat  reticulated  and  inclosing 
a  lakelet  and  some  shallower  kettleholes.  The  material  of  this  part  of  the 
plain  consists  of  gravel,  cobbles,  and  bowlderets,  all  well  rounded  and 
polished  by  water.  The  slopes  of  the  ridges  are  not  very  steep.  Passing 
south  and  southeast,  we  find  the  ridges  becoming  confluent  and  merging 
into  a  rather  level  terrace  or  plain.  The  material  at  the  same  time  becomes 
finer,  and  soon  passes  by  horizontal  gradations  into  sand,  some  of  which 
may  have  been  blown.  The  plain  is  situated  in  the  midst  of  a  rather  level 
region  at  an  elevation  of  about  150  feet.  The  Kennebec  Bay  of  that 
time  sent  out  an  arm  westward  and  covered  the  Cobbosseecontee  Valley  to 
Readfield.  The  salt  water  over  Litchfield  Plain  would  then  be  75  or  more 
feet  deep.  The  country  lying  south  and  east  of  the  plain  is  deeply  covered 
by  a  silty  marine  clay.  I  was  unable  to  determine  whether  the  sand  of 
the  plain  passes  into  this  clay  by  horizontal  transition.  In  places  this 
appeared  to  be  the  case ;  in  other  places  the  junction  was  quite  abrupt  and 
there  was  reason  to  suspect  blown  sand.  The  plain  is  about  a  half  mile  in 
diameter. 

At  Litchfield  Plain  streams  capable  of  transporting  bowlderets  15  to 
18  inches  in  diameter  were  so  checked  within  the  distance  of  half  a  mile 
that  they  could  no  longer  carry  even  their  fine  sand.  This  gradual  check- 
ing of  a  swift  stream  can  be  wrought  only  by  its  flowing  into  a  body  of 
comparatively  still  water.  Two  low  passes  lead  from  the  plain,  one  north- 
ward the  other  northwestward,  and  two  glacial  rivers  may  have  converged 
to  this  spot.  If  at  a  point  so  far  north  of  the  present  coast  these  streams 
had  flowed  into  a  glacial  lake,  there  would  probably  have  been  a  series  of 
similar  deposits  extending  southward  toward  the  sea.     I  have  been  able  to 


ISOLATED  OSAE-MOUXDS  OR  MASSIVES.  369 

find  no  other  gravel  deposit  for  10  miles  south  of  it,  and  the  nearest  on  the 
north  is  in  the  northern  part  of  Litchfield,  nearly  5  miles  away.  The  great 
thickness  of  the  marine  clay  in  the  vicinity  and  its  somewhat  sandy  or  silty 
character  testify  that  one  and  perhaps  two  glacial  streams  here  flowed  into 
the  sea  at  a  time  when  the  ice  front  had  retreated  to  this  point.  To  the 
northwest  of  the  plain  is  a  rather  steep  terrace  in  the  till,  which  may  be 
due  to  the  erosion  of  the  ground  moraine.  If  so,  this  would  be  more 
probably  performed  by  a  subglacial  than  by  a  superficial  stream.  The 
rapid  slowing  of  the  water  after  entering  the  sea  proves  that  the  streams 
were  not  large.  The  great  swiftness  of  a  small  stream  required  in  order  to 
transport  so  large  bowlderets  would  be  more  probably  attained  by  a  sub- 
glacial  stream  under  pressure  in  its  tunnel  by  the  water  behind  it. 

Elsewhere  are  described  two  short  eskers  or  kames  in  Amherst  (see 
pp.  117-118)  which  at  the  south  converge  into  a  small  plain  of  horizontally 
stratified  matter  sliowing  clearly  a  horizontal  transition  of  the  gravel  into 
They  are  at  the  foot  of  a  hill  sloping  south,  and  were  in  places  favorable 
for  crevasses.     They  are,  in  fact,  hillside  kames  situated  below  230  feet. 

The  class  of  kames  or  eskers  under  discussion  are  here  termed  isolated 
because  no  other  gravels  can  be  proved  to  have  been  deposited  by  the  same 
glacial  streams  to  which  these  are  due.  The  field  evidence  rather  favors 
the  hypothesis  that  they  were  deposited  by  subglacial  streams.  Besides, 
we  have  the  general  consideration  that  near  the  ice  front  crevasses  could 
sand  and  finally  into  marine  clay,  all  within  about  one-fourth  of  a  mile- 
freely  form  and  conditions  would  be  favorable  to  the  formation  of  sub- 
glacial channels. 

ISOLATED   OSAR-MOUNDS   OR  MASSIVES   I^OT  ENDING  IN^  MARIlSnE 
DELTAS  PROPER. 

These  deposits,  being  very  broad,  are  massives  or  mesas  rather  than 
ridges.  They  belong  to  the  region  below  former  sea  level.  One  of  these 
plains  is  found  about  2  miles  northwest  of  Freeport  Village.  It  is  soHd 
and  rather  level  on  the  top,  somewhat  uneven  of  surface,  but  with  no  reticu- 
lated ridges  or  kettleholes  proper.  The  smoothness  of  surface  may  be  in 
part  due  to  the  waves  of  the  sea  sweeping  over  it,  since  it  occupies  a  posi- 
tion where  it  would  be  much  exposed  to  the  waves  of  the  broad  bay  which 
then  covered  the  valley  of  Royal  River  to  the  south  of  it.     Judging  from 

MON  XXXIV 24: 


370  GLACIAL  GRAVELS  OF  MAINE. 

the  surface  appearances  at  a  few  small  excavations,  tlie  table-land  consists 
of  sand,  gravel,  and  cobbles  mixed  in  alternating  layers,  but  the  northern 
and  southern  parts  of  the  plain  do  not  vary  much  in  degree  of  fineness. 
The  transition  between  the  somewhat  lenticular  mass  of  gravel  and  the 
marine  clay  is  quite  abrupt,  proving  that  they  were  not  formed  simultane- 
ously. Whereas  in  the  delta  deposited  in  the  open  sea  the  coarse  sediments 
are  stratigraphically  continuous  with  the  marine  clays,  one  passing  into  the 
other  by  insensible  degrees,  in  the  case  of  the  plain  imder  consideration  • 
the  glacial  currents  were,  within  the  area  of  deposition,  not  checked  suffi- 
ciently to  cause  them  to  drop  their  clay  and  silt.  The  gravel  is  overlain  by 
the  clay,  but  they  are  plainly  of  different  origin  and  dates.  Such  a  mass 
as  this  must  have  been  deposited  in  a  gradually  enlarging  pool  or  lake 
within  the  ice.  The  inflowing  stream  did  not  flow  into  a  body  of  water  as 
large  as  the  whole  plain.  I  conceive  that  it  first  flowed  into  a  small  pool, 
which  it  partially  filled  with  sand,  gravel,  and  cobbles.  Subsequently,  as 
the  ice  was  melted  and  eroded,  the  water  of  the  glacial  stream  continued  to 
flow  in  the  space  between  the  enlarging  central  mass  of  gravel  and  the 
receding  ice.  Thus  the  floAV  was  never  checked,  as  it  would  have  been  if 
it  flowed  into  a  lake  as  large  as  this  one  finally  became.  This  sort  of 
structure  is  substantially  the  same  as  that  of  many  of  the  massive  plains 
that  make  the  discontinuous  systems  of  osars  and  the  discontinuous  portions 
of  the  osars.  The  more  important  features  of  the  class  are  their  solidit}' 
(freedom  from  kettleholes  and  reticulations)  and  their  coarseness  of  mate- 
rial, which  is  in  marked  contrast  with  the  horizontal  passage  into  the  finest 
sediment  characteristic  of  the  true  delta.  The  top  is  somewhat  convex,  but 
not  always  conspicuously  lenticular.  They  are  found  in  a  part  of  the  State 
where  subglacial  streams  abounded.  They  could  be  accounted  for  as  being 
formed  in  the  pool  where  a  superficial  stream  fell  down  a  crevasse,  or  where 
a  subglacial  stream  entered  a  pool  or  lake  within  the  ice.  We  know  that  a 
superficial  stream  can  make  such  a  pool.  In  case  of  a  subglacial  stream,  it 
is  more  difficult  to  account  for  the  pool.  It  is  possible  that  a  subglacial 
river  of  fresh  water  pouring  into  the  sea,  or  having  its  cliannel  obstructed 
for  any  other  reason,  would  under  some  conditions  be  forced  to  rise  up  the 
crevasses,  and  when  the  ice  became  thin  enough  it  could  outflow  upon  the 
ice,  or  such  a  rise  of  water  could  be  caused  by  a  gorge  in  the  tunnel.  This 
water,  now  being  exposed  to  the  sun,  would  become  warmed;  and  if  so, 


GLACIAL  MAEINB  DELTAS.  371 

would  in  time  form  the  pool.  The  problem  is  closely  connected  Avith  the 
general  subject  of  the  discontinuous  osars,  and  will  be  referred  to  again 
later. 

GLACIAL    MARINE   DELTAS. 

Before  proceeding  to  the  discussion  of  the  discontinuous  osars  it  will 
be  of  advantage  to  consider  the  general  characteristics  of  the  delta-plains 
deposited  by  glacial  rivers  in  the  sea.  They  are  here  named  "glacial  marine 
deltas."     (See  PI.  XXVII,  B,  opposite  p.  336.)     They  were  of  two  kinds. 

I.  Those  deposited  in  front  of  the  ice  in  the  open  sea.     This  class 
spread  outward  in  rounded   or  irregular  fan  shape  when  deposited  over 
broad  and  rather  level  plains  where  they  were  free  to  expand  in  all  direc- 
tions.    In  narrow  valleys  their  shapes  were  necessarily  determined  in  part 
by  the  adjacent  hills.     They  conspicuously  show  the  characteristic  hori- 
zontal transition  of  sediments  from  coarse  at  the  north  to  finer  toward  the 
south — that  is,  away  from  the  mouth  of  the   glacial  river.     The  surface 
slopes  gradually  downward  and  outward  radially  to  tlie  outer  edge  of  the 
delta,  but  in  tidal  waters  this  slope  is  much  more  gradual  than  on  the  land. 
The  sand  of  the  delta  passes  by  insensible  gradations  into  silt  and  silty 
clay,  which  in  turn  merges  into  fine  fossiliferous  clay.     In  the  region  of 
transition  between  the  sand  and  clay  the  two  deposits  have  the  same  sur- 
face level.      Thus  the  proof  is  conclusive  that  they  are  contemporaneous 
and  that  the  clay  is  a  continuation  of  the  coarser  parts  of  the  delta.     But 
while  logically  and  genetically  the  clay  is  part  of  the  delta,  yet  since  the 
sediments  of  the  glacial  streams  are  so  much  more  largely  composed  of 
sand,  gravel,   and  larger  stones  and  bowlders,  I  here  include  under  the 
term  "deltas"  only  that  portion  composed  of  coarser  matter.     Moreover,  the 
clayey  parts  of  the   dehas   are   so   mixed  with   clay   derived  from  wave 
erosion  of  the  till,  also  with  the  clay  brought  down  by  the  swollen  rivers 
of  land  th-ainage  at  the  close  of  the  Glacial  period,  that  it  is  difficult  to 
distinguish  the  glacial  from  the  other  clays.     So  also  the  delta  clays,  being 
scattered  up  and  down  the  coast,  often  blend  with  one  another,  and  the 
separate  deltas  are  indistinguishable.     It  is  noticeable  that  the  clays, are 
thicker  near  the  mouths  of  the  glacial  rivers,  and  doubtless  the  spirit  level 
will  sometimes  reveal  where  the  mouths  of  the  rivers  were  in  cases  where 
to  the  unassisted  eye  the  deltas  are  confluent.     In  mapping  the  marine 
deltas  it  has  been  a  matter  of  difficulty  to  determine  where  sand  ends  and 


372  GLACIAL  GRAVELS  OF  MAINE. 

clay  begins.  The  only  way  to  secure  accuracy  is  by  micrometric  measure- 
ments of  tlie  size  of  the  grains. 

An  interesting  marine  delta  is  in  the  valley  of  the  west  branch  of  the 
Union  River,  in  Aurora.  It  is  locally  known  as  the  Silsby  Plains,  and  is 
elsewhere  described.  The  valley  of  Union  River  was  at  one  time  occupied 
by  an  arm  of  the  sea  from  1  to  8  miles  broad.  Into  this  inlet  the  great 
Katahdin  osar  river  for  a  time  poured  nearly  at  right  angles.  A  delta  of 
gravel  and  sand  formed  in  front  of  its  mouth.  This  delta  extended  across 
the  whole  breadth  of  the  valley  then  under  the  sea,  and  for  4  miles  south- 
ward and  nearly  a  mile  north  of  the  mouth  of  the  glacial  river.  The  last- 
named  fact  indicates  strong  tidal  currents  on  the  coast  of  Maine  at  that  time. 
If  the  Bay  of  Fundy  was  at  this  time  a  strait  connecting  the  Grulf  of  Maine 
with  the  Gulf  of  St.  Lawrence,  the  tides  would  probably  not  be  so  high  in 
eastern  Maine  as  now;  yet  here  is  evidence  of  considerable  tidal  action. 
Tidal  currents  sweeping  along  the  coast  would  tend  to  mix  the  clay  portions 
of  the  deltas  of  the  glacial  rivers. 

11.  Another  class  are  here  termed  "ice-bordered"  or  "narrow  marine" 
deltas.  They  are  usually  much  longer  from  north  to  south  than  from  east 
to  Avest,  having  but  little  of  the  fan  shape.  At  their  southern  ends  they  pass 
by  degrees  into  clays  having  the  same  level,  like  the  delta-plains  above 
described.  They  are  found  in  valleys  or  level  regions  much  broader  than 
they  are,  where  there  is  no  topographical  reason  why  a  delta,  if  deposited 
in  the  open  sea,  should  not  have  spread  outward  in  fan  shape.  Except  at 
the  southern  extremity,  the  sand  and  gravel  end  abruptly.  The  east  and 
west  flanks  commonly  form  a  steep  bank  or  bluff  rishig  sometimes  as  much 
as  20  feet  above  the  marine  clay  which  here  covers  the  base  of  the  gravel 
plain.  The  transition  from  the  coarse  matter  of  the  plain,  such  as  sand, 
gravel,  cobbles,  etc.,  to  the  clay  at  the  sides  of  the  plain  is  very  abrupt. 
Very  evidently  the  clay  was  deposited  later  than  the  coarse  matter  at  all 
points  of  the  plain  except  on  the  south.  Evidently  the  glacial  rivers  flowed 
in  channels  which  were  open  toward  the  ocean,  but  at  the  sides  were  bor- 
dered by  ice  which  covered  the  rest  of  the  valleys  and  prevented  the  delta 
from  spreading  oixt  into  fan  shape.  At  one  time  I  described  these  deltas  as 
being  formed  in  bays  within  tlie  ice,  into  which  the  tidal  watei-s  extended 
as  they  do  into  an  estuary.  They  are  all  situated  below  the  contour  of  230 
feet,  and  if  they  were  deposited  at  the  time  the  sea  stood  at  its  highest  level 


GLACIAL  MAEINE  DELTAS.  373 

these  broad  channels  in  which  the  narrow  deltas  were  deposited  would 
indeed  be  estuaries.  On  further  reflection  I  find  they  can  also  be  accounted 
for  as  having  been  deposited  in  broad  ice  channels  at  a  time  when  the  sea 
stood  not  at  its  highest  elevation  but  at  the  level  of  the  delta  itself,  or  per- 
haps at  the  place  of  transition  from  gravel  to  sand.  The  ice  front  then 
stood  at  or  near  the  place  of  transition  from  sand  to  clay,  where  the  clay 
of  the  local  delta  merges  in  the  general  sheet  that  covers  all  the  coast.  On 
this  conception  Ave  have  in  the  narrow  deltas  a  type  of  the  sediments 
poured  into  the  sea  or  formed  at  or  near  sea  level  during  a  rise  of  the  sea 
accompanied  by  melting  of  the  ice  as  it  advanced.  If  so,  we  could  expect, 
on  sloping  shores,  and  where  the  flow  of  the  glacial  stream  continued 
marine,  a  delta  to  extend  backward  from  the  outer  one,  up  to  the  level  of 
230  feet.  Such  a  recession  would  show  finer  sediments  overlying  the  earlier 
and  coarser  ones,  since  at  any  given  point  the  water  would  be  growing 
deeper  and  the  distance  to  the  shore  greater  as  the  sea  rose  to  its  highest 
level.  It  is  doubtful  if  the  facts  thus  far  observed  make  it  possible  to 
decide  positively  between  the  two  hypotheses,  and  indeed  narrow  marine 
deltas  may  have  been  formed  in  both  of  these  ways.  On  either  hypothesis 
the  delta  as  we  go  southward  was  bordered  laterally  by  ice  until  we  reach 
the  place  where  the  delta  clay  merges  into  the  broader  clay  sheet  of  the 
coast.  As  the  ice  retreated  and  the  delta  channel  broadened,  clay  was  laid 
down  over  the  valleys  at  the  sides  of  the  original  ice-bordered  delta.  The 
currents  would  naturally  be  swifter  in  front  of  the  main  channel.  For  this 
or  some  other  reason  the  later-deposited  clay  was  thin  or  lacking  on  top  of 
the  sand-and-gravel  portions  of  these  as  well  as  on  the  broad  or  fan-shaped 
deltas. 

That  the  clay  into  which  the  marine  delta-plains  pass  by  insensible 
gradations  is  a  true  marine  sediment  is  evidenced  by  the  following  facts: 

1.  The  clay  extends  continuously  from  the  delta-plains  to  the  present 
seacoast,  a  distance  of  10  to  30  miles,  and  in  a  few  cases  even  a  greater 
distance. 

2.  This  clay  thus  is  continuous  with  the  clay  that  surrounds  the  beach 
gravels.     We  can  not  separate  them. 

3.  In  many  places  this  clay  contains  marine  fossils.  Near  the  belt  of 
transition  between  the  g-lacial  delta  sands  and  the  clays  I  have  not  been 
able  to  find  fossils,  but  within  2  or  3  miles  south  from  that  point  fossils 


374  GLAGIAL  GRAVELS  OF  MAINE. 

have  been  found  in  digging'  wells.  The  nearest  I  have  found  fossils  to  a 
large  marine  delta  is  about  4  miles.^ 

4.  The  deltas  here  described  are  all  found  below  the  elevation  of  about 
230  feet,  except  those  situated  farthest  northwest,  which  may  have  a  higher 
elevation.  Up  to  these  levels  the  beaches  are  distinctly  and  incontestibly 
to  be  found. 

6.  This  clay  covers  the  whole  of  the  State  up  to  that  elevation — that 
is,  all  the  broader  valleys  and  such  places  as  would  not  form  projecting 
headlands  of  the  expanded  sea. 

6.  The  sand  and  gravel  portions  of  adjacent  marine  deltas  are  often 
confluent  or  nearly  so,  proving  that  they  were  deposited  in  the  same  body 
of  water.  In  York  and  Cumberland  counties  there  is  a  succession  of 
practically  confluent  delta-plains  for  about  40  miles. 

Marine  delta-plains  form  part  of  both  the  osars — the  broad  osars  and 
the  discontinuous  osars — and  they  form  the  usual  termination  of  the  great 
plains  of  reticulated  kames.  The  Katahdin  system  expands  into  two  deltas 
deposited  in  the  open  sea:  first,  in  the  level  region  west  and  northwest 
of  Deblois ;  second,  in  the  valley  of  Union  River  in  Aiu-ora.  It  also 
expands  into  a  delta  in  Greenfield,  30  miles  farther  north,  but  I  am  some- 
what in  doubt  whether  the  last  named  is  a  glacial  marine  or  a  lacustrine 
delta.  In  like  manner  most  of  the  longer  gravel  systems  show  from  one  to 
tlu-ee  marine  deltas  at  difiPerent  distances  from  the  coast.  These  must  mark 
either  the  retreat  of  the  ice  northward  or  an  increase  of  elevation  of  the 
sea,  or  both  causes  combined. 

One  fact  regarding  the  deltas  here  denominated  "glacial  marine" 
deserves  special  notice.  By  far  the  largest  of  the  delta-plains  are  found 
between  170  and  250  feet  above  the  present  sea  level.  The  high  level  deltas 
cover  hundreds  of  square  miles.  They  prove  that  the  time  of  most  active 
transportation  of  glacial  sediments  coincided  with  the  time  when  the  open 
sea  covered  all  or  nearly  all  the  coast  region  of  the  State  below  the  contour 
of  230  feet.  They  are  so  extensive  and  unmistakable  in  character,  and 
all  along  the  coast  have  so  nearly  the  same  relative  development  at 
that  contour  that  they  form  an  important  part  of  the  e\ddence  as  to  the 

•  A  leaf  of  sea-lettuce  (  Ulva  lactuca)  found  in  the  upper  clays  at  Lewiston.     The  lower  layers  of 
the  clays  are  richly  fossiliferous  at  Lewiston.     The  marine  delta  was  situated  not  far  north  and  east 
-of  Lake  Auburn. 


GLACIAL  MARINE  DELTAS.  375 

highest  level  of  the  sea  in  the  coast  region.  Marine  clays  and  these 
so-called  marine  deltas  are  found  at  all  elevations  up  to  about  230  feet  near 
the  coast,  but  the  deltas  have  their  maximum  development  as  we  approach 
that  contour.  Above  that  elevation  the  deltas  are  few  and  rather  small, 
and  are  situated  in  the  interior  valleys.  They  are  found  at  no  prevailing 
elevation,  and  they  are  local,  not  confluent  like  the  great  deltas  found  at 
230  feet  or  not  far  above  and  below.  The  locality  before  named  in  York 
and  Cumberland  counties  is  the  best  place  for  the  study  of  the  confluent 
marine  deltas.  To  the  careful  observer  in  the  southern  parts  of  the  State 
the  contrasts  between  the  surface  deposits  and  characteristic  scenery  above 
the  level  of  about  230  feet  and  those  below  that  level  is  very  great.  In 
passing  from  one  of  these  regions  to  the  other  we  find  a  change  such  as  in 
human  affairs  would  be  termed  a  revolution.  The  contrast  is  greater  near 
the  mouths  of  the  great  glacial  rivers  than  away  from  them.  It  should  be 
noted  in  this  connection  that  the  opinion  is  elsewhere  expressed  that  the  sea 
stood  at  higher  levels  50  or  more  miles  from  the  present  coast  than  along 
the  outer  coast  itself. 

In  the  above  discussion  it  is  assumed  that  the  broad  rounded  or  fan- 
shaped  deltas  were  deposited  in  the  open  sea.  It  is  a  possible  hypothesis 
that  they,  as  well  as  the  narrow  marine  deltas,  were  formed  subglacially,  in 
places  where  the  subglacial  channels  had  enlarged  themselves  laterally  as 
they  entered  the  sea,  so  that  broad  portions  of  the  ice  were  undermined  and 
floated  on  the  sea  water.  This  would  make  the  ice  approach  the  condition 
of  glaciers  which  flow  into  a  warm  sea,  where  they  are  melted  from  beneath. 

1.  The  Waldoboro  and  other  short  peripheral  moraines  prove  that  the 
lower  portions  of  the  ice  contained  much  morainal  matter,  though  we  do  not 
know  how  great  a  height  it  attained.  Unless  the  supposed  broad  subglacial 
river  should  melt  all  the  part  of  the  ice  containing  morainal  matter,  there 
would  still  remain  till  in  the  ice  above  the  channel.  As  the  undermelted  ice 
fell  off  in  icebergs,  more  or  less  of  this  d(^bris  would  fall  upon  the  under- 
lying gravel  and  sand.  The  delta-plains  are  covered  by  no  sheet  of  till, 
though,  like  the  marine  clays  and  all  the  rest  of  the  country  below  230  feet, 
they  are  strewn  with  occasional  bowlders,  which  I  attribute  to  ice  floes. 

2.  The  supposed  caves  beneath  the  ice  must  have  been  of  mammoth  size 
More  than  a  score  of  the  deltas  contain  a  surface  of  more  than  5  square 
miles  each,  and  several  of  them  contain  two  or  thi-ee  times  that  area. 


376  GLACIAL  GEAVELS  OF  MAINE. 

3.  The  deltas  of  different  streams  are  sometimes  confluent.  This  lact 
still  more  enlarges  the  continuous  areas  of  supposed  floating  ice. 

4.  Unless  the  till  were,  in  New  England,  confined  to  the  very  bottom 
of  the  ice,  the  till  contained  in  the  ice  above  the  limit  of  supposed  melting 
would  greatly  increase  the  specific  gravity  of  the  floating  ice.  It  is  not 
proved  that  till-containing  ice  could  be  sustained  by  flotation  in  so  shallow 
water.  Out  in  the  Gulf  of  Maine  at  a  great  depth  the  buoyancy  of  the 
purer  upper  ice  would  enable  a  thick  sheet  of  till-bearing  ice  to  float.  But 
the  largest  of  the  glacial  marine  deltas  are  situated  near  the  contour  of  230 
feet,  where  the  water  would  be  less  than  100  feet  deen.  Only  a  thin  sheet 
of  pure  ice  could  float  under  these  circumstances. 

5.  In  the  case  of  the  Silsby  Plains  in  Aurora,  mentioned  above,  we 
have  proof  of  tidal  action,  and  most  of  the  deltas  spread  outward  so  rapidly 
as  to  indicate  the  cooperation  of  the  tides  in  the  work  of  strewing  tlie 
sediment  of  the  glacial  rivers  up  and  down  their  valleys  and  along  the  coast 
and  out  to  sea.  Tidal  cun-ents  in  the  open  sea  would  do  this  work.  It  is 
uncertain  what  would  be  the  action  of  the  tides  on  the  sediments  beneath 
floating  ice,  since  the  free  space  beneath  the  ice  would  change  with  the 
state  of  the  tide  and  the  thickness  of  ice. 

6.  The  rise  and  fall  of  the  tides  would  cause  a  strain  on  the  central 
parts  of  the  supposed  undermelted  ice  such  that  from  time  to  time  small 
bergs  would  break  off"  and  float  away  to  sea.  Thus,  even  if  the  bottom 
ice  were  melted  over  so  large  areas  the  upper  ice  would  soon  disappear  and 
the  supposed  cave  would  become  a  part  of  the  open  sea. 

The  difficulties  of  the  hypothesis  of  large  areas  of  undermelted  ice 
are  so  great  that  the  hypothesis  that  the  marine  deltas  were  laid  down  over 
the  bottom  of  the  open  sea  I  consider  by  far  the  best  interpretation,  though 
the  margins  of  the  ice  channels  would  be  undermelted,  just  as  they  were 
on  the  land. 

SYSTEMS   OF  DISCONTINUOUS   OSARS. 

In  this  class  a  number  of  short  ridges,  often  plain-like,  have  a  linear 
arrangement  and  other  relations  such  that  they  are  regarded  as  having  been 
deposited  by  the  same  glacial  river.  These  systems  have  nearly  the  same 
general  directions  as  the  continuous  osars,  and  their  topographical  relations 
are  substantially  the  same.  The  osars  as  they  approach  the  coast  become 
discontinuous,  like  the  systems  now  to  be  described.     In  the  case  of  the 


ti 


F/i.  ^^^ 


SYSTEMS  OF  DISCONTINUOUS  OSARS.  377 

osars  there  can  be  no  doubt  of  the  action  of  a  single  glacial  river,  even 
when  the  ridge  becomes  inten-upted.  The  feature  of  noncontinuity  can 
not,  therefore,  in  itself  be  urged  as  proving  the  action  of  more  than  a  single 
stream.  Genetic  connection  is  to  be  proved  or  disproved  by  general  con- 
siderations, the  nature  of  which  has  been  referred  to  elsewhere. 

The  feature  of  systematic  noncontinuity  is  almost  wholly  confined  to 
the  coast  region.  The  longer  osars  and  osar-plains  frequently  extend  10  to 
30  miles  south  of  the  contour  of  230  feet  before  they  become  discontinuous, 
but  the  discontinuous  character  rarely  extends  north  of  that  contour,  and 
then  usually  in  a  modified  form  approaching  the  osar  type  (e.  g.,  at  North 
Monmouth). 

In  the  noncontinuous  systems  the  gravel  deposits  are  from  a  few  feet 
up  to  3  miles  long,  and  they  are  separated  by  intervals  varying  within  the 
same  limits.  The  intervals  between  the  successive  deposits  are  a  constant 
a,nd  distinguishing  feature  of  the  class.  The  intervals  are  due  to  the  original 
manner  of  deposition.  Ridges  formed  by  the  imequal  erosion  of  a  contin- 
uous plain  are  not  entitled  to  the  same  name  as  ridges  that  were  originally 
formed  in  substantially  the  same  shapes  they  have  at  present.  For  this 
reason  the  terms  "kame"  or  "osar"  are  not  in  this  report  apphed  to  ridges 
consisting  of  portions  of  the  valley  drift  or  other  alhudal  plains  which  have 
been  left  as  ridges  simply  because  the  surrounding  matter  has  been  eroded. 
The  gravel  masses  under  discussion  have  sometimes  been  eroded,  but  the 
erosion  can  readily  be  traced,  and  it  can  be  asserted  with  greatest  confi- 
dence that  no.  continuous  mass  of  gravel  ever  connected  them.  This  is 
the  more  certain  because  they  are  mostlj^  situated  in  the  region  that  was 
under  the  sea  and  the  gravels  are  wholly  or  partly  covered  by  marine  clay, 
which  would  protect  them  from  erosion.  Any  agency  which  would  erode 
the  gravels  must  first  erode  the  overlying  clay.  But  in  most  places  the 
clay  still  remains  or  has  only  partially  been  eroded.  In  some  cases  ridges 
which  appear  to  be  discontinuous  may  really  be  connected  by  a  low  ridge 
now  covered  from  sight  by  the  clay.  But  in  many  places  streams  flow 
across  the  space  between  the  apparently  separate  deposits  of  the  same 
system,  and  in  their  banks  no  gravels  are  seen,  though  they  cut  down  to  the 
till  or  even  to  the  underlying  rock. 

Any  satisfactory  explanation  of  the  discontinuous  osars  must  account 
not  only  for  the  deposition  of  the  gravels  but  also  for  the  intervals  between 


378  GLACIAL  GRAVELS  OF  MAINE. 

the  gravels.  Here  arise  special  difficulties.  The  gravels  afford  much  posi- 
tive evidence  regarding  themselves,  but  in  accounting  for  the  gaps  in  these 
systems  we  have  to  rely  largely  on  negative  evidence.  Probably  no  other 
problem  connected  with  the  glacial  gravels  is  so  difficult  of  solution.  It 
will  be  seen  that  a  discussion  of  the  origin  of  the  gaps  in  the  discontinuous 
systems  will  apply  almost  equally  to  the  discontinuous  portions  of  the  osars 
and  broad  osars.  Indeed,  if  the  streams  which  deposited  the  discontinuous 
kamea  had  been  longer,  so  as  to  extend  farther  north,  nearer  the  n^ve,  I 
believe  that  toward  their  northern  extremities  the  separate  ridges  would  be 
confluent  and  not  distinguishable  from  the  osars  and  broad  osar  terraces. 

The  deposits  forming  the  noncontinuous  osars  are  of  several  quite  dis- 
tinct types. 

1.  Marine  deltas.  The  general  characteristics  of  these  plains  have 
already  been  described.  The  longer  of  the  systems  under  discussion  almost 
always  expand  into  one  or  two  marine  deltas ;  some  of  the  shorter  systems 
also  contain  deltas,  but  more  of  them  have  none.  The  deltas  are  found  at 
intervals  of  several  miles.  Thus  far  I  have  not  been  able  to  find  terminal 
moraines  genetically  connected  with  the  marine  deltas,  though  there  is 
much  reason  to  suspect  this  relation  at  the  Waldoboro  moraine;  yet  I  have 
often  suspected  their  existence  beneath  the  marine  clays.  These  clays  are 
sometimes  80  to  100  feet  deep,  and  large  ridges  might  exist  which  are  now 
hidden  by  the  clays. 

2.  Broad  solid  ridges  or  gravel  massives  one-eighth  of  a  mile  or  more 
in  breadth,  separated  by  the  usual  intervals.  They  sometimes  have  a  some- 
what uneven  surface,  at  other  times  are  rather  smooth  and  with  slightly 
convex  surface.  In  external  appearance  they  somewhat  resemble  the  small 
deltas,  but  the  horizontal  assortment  of  sediments  is  much  less  perfect. 
They  usually  rise  above  the  clay,  and  they  do  not  pass  into  it  by  degrees. 
Even  at  their  southern  border  the  material  is  often  quite  coarse,  and  never 
finer  than  medium  sand.  The  clays  overlie  these  gravels  at  their  bases  and 
are  plainly  a  later  deposit;  at  least  these  are  their  relations  on  the  surface. 
It  is  possible  that  in  some  cases  a  lower  stratum  of  these  plains  passes  into 
the  clays  by  horizontal  transition;  but  if  so,  the  stratum  showing  that  transi- 
tion is  buried  out  of  sight.  Often  the  exposures  show  conclusively  that 
there  is  no  such  transition,  and  nowhere  is  there  proof  of  it. 

This  sort  of  solid  or  massive  hills  closely  resembles  the  plain  before 


GLACIAL  GRAVELS  OF  COASTAL  REGION.  379 

described  near  Freeport  (pp.  369-370).  It  will  be  convenient  to  refer  to 
them  as  gravel  massives.  They  are  not  so  common  a  feature  of  the  discon- 
tinuous osars  as  of  the  long  osar  and  broad  osar  systems. 

3.  Reticulated  eskers  consisting  of  two  or  more  reticulated  ridges 
Inclosing  kettleholes,  but  not  ending  in  delta-plains,  such  as  the  gravels 
near  East  Monmouth.  These  are  a  not  uncommon  form  of  the  gravels. 
The  material  is  nowhere  very  fine,  showing  that  the  waters  were  not  much 
checked.     The  problem  of  the  reticulations  will  be  referred  to  hereafter. 

4.  Cones,  domes,  and  lenticular  short  ridges,  all  with  broadly  arched 
cross  section.  As  a  class  these  deposits  have  rather  gentle  latei-al  slopes 
and  their  shapes  resemble  the  drumHns  or  lenticular  hills  of  till.  The 
variety  of  individual  forms  is  very  great.  All  gradations  can  be  found 
between  domes  and  lenticular  mounds  on  the  one  extreme  and  long  ridges 
on  the  other.  While  they  vary  in  size,  height,  and  slope,  yet  the  prevail- 
ing lateral  slopes  of  the  gravels  that  were  below  the  sea  are  more  gentle 
than  those  above  that  level. 

GLACIAL    GRAVELS    OF    THE    COASTAL   REGION. 
RELATIONS   OP   &LAOIAL    GRAVELS   TO    THE   FOSSILIFEROUS   MARINE   BEDS. 

The  glacial  gravels  are  found  in  three  relations  to  the  marine  clays. 
First.  The  gravels  have  the  same  level  as  the  clays  and  pass  by  degrees 
directly  into  them.  This  is  the  characteristic  relation  of  the  glacial  deltas 
and  marks  the  coarser  glacial  sediments  as  being  laid  down  simultaneously 
with  the  clays.  Second.  The  clays  overlie  the  glacial  gravels,  either  wholly 
covering  them  or  covering  their  base.  The 
gravels  were  first  deposited  within  ice  walls, 
and  subsequently,  after  the  ice  had  melted, 
the  clays  were  deposited.  This  arrange- 
ment is  so  common  that  for  a  long  time  1 
supposed  it  and  the  third  named  to  be  the 

1  j_l         /»       J     1       •  ,      1     />  Fig,  27. — Sheet  of  marine  clay  overlvina;  osar. 

only  ones,  the  first  being  accounted  for  as 

due,  not  to  original  deposition,  but  to  the  subsequent  action  of  the  sea 
in  remodeling  the  sediments.  This  was  based  on  an  exaggerated  idea  of 
the  power  of  the  sea  to  erode  and  transport.  Third.  The  sand  and  gravel 
of  the  upper  parts  of  the  osar  gravels  overlie  the  fossiliferous  clays  which 
cover  the  bases  of  the  same  kames  or  osars.     This  happens  in  many  cases, 


380 


GLACIAL  GRAVELS  OF  MAINE. 


but,   so  far  as   I  have   noted,  only  in  places  where  the  ridges  would  be 
exposed  to  the  surf.     The  fact  could  be  accounted  for  in  two  ways : 

1.  The  ridges  were  first  deposited  within  ice  walls.  Subsequently  the 
ice  melted  and  sea  water  covered  the  ridges.  Marine  clay,  or  in  some  cases 
kame  or  osar  border  clay,  was  now  laid  down,  covering  the  bases  of  all  the 
ridges  and  the  whole  of  the  smaller  ridges  or  osars,  and  a  thin  sheet  of 
clay  may  have  been  spread  over  the  tops  of  even  the  highest  ridges  that 
were  under  the  sea.     During  the  retreat  of  the  sea  to  its  present  level  the 

surf  must  have  suc- 
cessively beat  upon 
every  pai't  of  the 
land  as  it  emerged 
from  the  water.     In 


exposed  situations 
the  waves  would  be 
able  to  erode  the  upper  portions  of  such  gravel  masses  as  rose  above  the  clays 
and  to  leave  the  matter  in  quaquaversal  or  anticlinal  stratification  along  the 
lower  slopes  of  the  ridges  and  extending  out  a  few  feet  or  yards  over  the  clay 
previously  deposited  upon  the  base  of  the  gravel.  In  Carmel,  Clinton, 
Detroit,  and  many  other  towns,  wells  dug  in  the  flanks  of  the  osars  almost 
invariabl}^  are  dug  through  a  thin  stratum  of  gravel,  then  through  clay 
containing  shells,  and  finally  into  a  deep  stratum  of  gravel  in  which  water 
is  found.     The  upper  gravel 


Fig.  28. — Marine  clay  ' 


verlying  base  of  osar,  and  itself  covered  witli  a  capping  of 
gravel;  Corinth. 


Fig.  29. — Marine  clay  and  sand  in  tbe  midst  of  osar  gravel;  Hermon  Pond. 


extends  only  a  short  dis- 
tance from  the  central  ridge. 
2.  According'  to  an- 
other theory,  the  sand  and 
gravel  which  overlie  the  clay  on  the  flanks  of  the  osars  may  have  been 
brought  thei-e  by  glacial  streams.  On  this  theory  some  of  the  coarser 
matter  was  swept  out  to  sea  for  short  distances  beyond  the  retreating  ice 
front  and  deposited  over  the  marine  clays  that  had  already  been  laid  down 
in  the  open  sea.  The  theory  would  make  the  sand  and  gravel  overlying 
the  marine  clay  a  sort  of  marine  delta.  The  subject  will  be  discussed  more 
fully  later.  If  the  glacial  gravel  at  Portland  overlies  the  fossiliferous 
marine  clays,  it  may  do  so  in  the  manner  here  indicated,  or  if  at  the  base 
it  overlies  the  clays,  this  would  form  a  fourth  arrangement  of  the  gravels 


GLACIAL  GRAVELS  OF  COASTAL  EEGION.  381 

and  clays.  The  difficulty  of  accounting  for  the  deposition  of  gravel  in  the 
open  sea  without  the  formation  of  a  delta  is  very  great,  if  not  insuperable. 

A  very  important  fact  to  be  noted  relates  to  the  size  of  the  gravel 
deposits  at  different  elevations  and  distances  from  the  coast.  The  osars  and 
broad  osars  become  discontinuous  at  or  below  the  contour  of  230  feet,  but 
the  longer  gravel  systems  are  continuous  farther .  south  than  the  shorter 
ones.  But  no  matter  how  large  the  gravel  systems  are,  they  all  become 
discontinuous  before  reaching  the  present  shore  of  the  sea.  Invariably  the 
size  of  the  osars  and  osar  terraces  becomes  smaller  as  we  go  south  from  the 
contoiu-  of  230  feet,  and  the  intervals  between  the  successive  deposits 
increase.  This  remark  applies  to  the  solid  ridges  and  domes.  The  marine 
deltas  which  here  and  there  appear  in  the  midst  of  the  line  of  lenticular 
ridges  interrupt  the  symmetry  of  the  development,  since  they  are  much 
larger  than  the  ridges  and  domes  situated  in  the  series  both  north  and 
south  of  them.  But  measured  among  themselves,  as  a  class,  the  marine 
deltas  are  largest  near  the  con- 
tour of  230  feet  and  diminish  in 
size  southward.  This  rule  can 
not  always  be  proved — as,  for 
instance,  in  case  of  the  Katahdin  F'«-  3»-m^"°«  ^i^'.v  "ve.i.vins  base  of  o.sar;  Ha.npiien. 

system,  where  the  deltas  are  situated  in  different  drainage  basins  and  it 
is  difficult  to  compute  the  average  depth  of  the  delta.  Apparently  the 
delta  west  and  northwest  of  Deblois  is  the  largest  of  the  system.  It  is  that 
which  is  situated  farthest  south.  But  the  case  is  complicated  by  the  fact 
that  the  Seboois-Kingman  system  may  have  helped  form  this  delta,  and 
also  by  the  fact  that  it  rises  nearer  the  230-foot  level  than  the  Silsby  Plains 
situated  20  miles  northwest.  The  great  development  of  the  glacial  sedi- 
ments not  far  from  the  contour  of  230  feet  is  still  further  aided  by  several 
of  the  larger  gravel  systems  of  the  Androscoggin  Valley  which  come  down 
to  near  or  a  little  below  that  elevation  and  then  end — the  Chestei'ville- 
Leeds,  Canton-Auburn,  Peru-Buckfield,  and  Sumner-Minot  systems. 

In  most  cases  the  gravel  systems  of  all  types  end  before  they  reach 
the  line  of  the  present  coast.  The  ridges  grow  shorter  and  smaller  till  they 
are  only  heaps  10  to.  15  feet  high,  while  the  intervals  between  them  grow 
on  the  average  larger.  In  Western  phrase,  the  gravels  ''peter  out."  The 
only  places  where  they  plainly  end  in  bluffs  on  the  shore  are  at  the  north 


382  GLACIAL  GKAVELS  OF  MAINE. 

ends  of  bays  or  fiords  considerably  north  of  the  general  coast  line.  Thus 
two  systems  end  in  Belfast  Bay  and  one  in  the  north  end  of  Penobscot 
Bay.  The  Clinton  system  ends  very  near  the  fiord  known  as  Sheepscot 
River,  and  another  comes  almost  to  Cobscook  Bay,  in  Pembroke,  and 
another  near  the  sea  at  Waldoboro.  Since  the  deposits  become  smaller 
toward  the  south,  it  ia  possible  that  some  of  the  systems  reall}^  extend 
farther  than  they  seem,  the  small  deposits  of  gravel  which  form  their 
southern  ends  being  covered  by  the  marine  clays.  But  in  many  cases  this 
can  not  be  admitted.  Thus  three  systems  seem  to  end  near  the  Head  of 
the  Tide,  Belfast.  One  of  them,  if  extended,  would  be  found  beneath  Bel- 
fast Bay,  but  the  two  more  westerly  systems  would  cross  the  city  of  Belfast, 
where  excavations  for  wells,  foundations,  etc.,  are  so  numerous  that  the 
gravels  would  certainly  have  been  discovered.  In  these  cases  and  in  most 
of  the  gravel  systems  the  evidence  that  they  really  end  before  reaching  the 
sea  is  satisfactory.  Another  exception  is  found  on  the  coast  from  Scarboro 
for  many  miles  southward.  The  shore  is  formed  of  marine-delta  sand.  It 
is  difficult  to  estimate  how  far  the  delta  originally  extended  out  into  the 
region  at  present  covered  by  the  ocean.  In  Jonesport  a  plain  of  glacial 
sand  reaches  nearly  to  tide  water.  With  the  exceptions  named  the  gravel 
systems  all  end  north  of  the  present  shore,  and  in  most  cases  only  10  to  50 
feet  above  sea  level. 

LENTICULAR  SHAPE  OF  THE  COASTAL  GRAVEL  MASSES. 

At  Winslows  Mills  a  round-topped  hummock  of  glacial  gravel  lies 
directly  beneath  the  more  northern  ridge  of  tlie  Waldoboro  moraine.  It 
was  exposed  by  excavations  made  during  the  building  of  the  dam  and  mills. 
At  the  time  of  m.j  visit  the  gravel  had  fallen  into  the  excavation  so  as  to 
make  it  impossible  to  determine  what  was  the  original  nature  of  the  stratifi- 
cation. Enough  could  be  seen  of  the  general  shape  of  the  mass  of  gravel 
and  cobbles  to  show  that  it  does  not  materially  differ  in  external  form  from 
the  other  hillocks  of  the  system  of  glacial  gravel  of  which  this  forms  a  part. 
This  is  a  discontinuous  system  which  extends  from  near  the  sea  at  Waldo- 
boro northward  along  the  valley  of  the  Medomac  to  a  point  somewhat  more 
than  a  mile  north  of  the  moraine  at  Winslows.  The  moraine  lies  directly 
on  the  gravel  dome,  without  transition  beds.  I  could  discover  no  sign  that 
the  glacial  stream  which  deposited  the  gravel  was  flowing'  at  the  time  the 


LENTICULAR  SHAPE  OF  COASTAL  GRAVEL  MASSES. 


383 


moraine  was  itself  deposited.  The  moraine  near  the  esker  showed  no  more 
sign  of  water  wash  than  at  a  distance.  The  lenticular  eskers  or  short  osars 
extend  about  3  miles  south  of  the  moraine  and  along  a  curved  valley.  We 
can  not  admit  that  these  small  hummocks  separated  by  intervals  of  one-fourth 
mile  or  less  could  be  formed  in  the  open  sea  by  a  glacial  stream  issuing 
from  the  ice  front  while  the  moraine  was  forming.  Their  materials  as  well 
as  their  shapes  testify  that  the}*  were  formed  within  ice  walls  by  currents 
that  at  no  time  were  checked  as  they  would  have  been  if  poured  into  the  open 
sea.  The  hummock  underneath  the  moraine  has  the  proper  shape,  size, 
position,  and  composition  of  one  of  the  parts  of  this  system.     If  at  this  point 


Fig.  31.— Leuticular  esker  flanked  -with  blowing 


a  subglacial  river  continued  to  flow  during  the  time  the  moraine  was  being 
formed,  it  ought  to  have  more  or  less  washed  away  the  moraine  and  left,  not 
a  line  of  discontinuous  hummocks  separated  by  intervals,  but  continuous 
ridges  or  delta-plains  of  frontal  gravel  extending  south  from  the  moraine. 
The  same  would  be  true  of  a  superficial  stream.  This  makes  it  probable 
that  there  is  no  genetic  connection  between  the  hummock  that  underlies  the 
moraine  and  the  moraine  itself  More  probably  the  gravel  system  had  all 
been  deposited  prior  to  the  moraine,  and  at  the  time  of  the  moraine  the 
glacial  stream  had  ceased  to  flow  in  this  part  of  its  former  channel,  or  was 
too  feeble  to  form  such  deposits. 

It  is  possible  that  the  Waldoboro  moraine  was  due  to  an  advance  of 


384  GLACIAL  GRAVELS  OF  MAINE. 

the  ice  after  it  had  once  retreated  northward  of  this  point.  Any  great 
readvance  would  imply  general  or  climatic  increase  of  intensity  of  glacial 
conditions.  If  so,  we  ought  to  find  similar  moraines  all  along  the  coast. 
The  few  short  moraines  certainly  demand  pauses  in  the  retreat  of  the  ice, 
and  they  may  indicate  a  readvance.  In  either  case  the  moraine  must  have 
been  formed  while  the  ice  was  in  motion.  The  conclusion  follows  that  if 
the  ice  was  not  stagnant  at  the  time  of  the  moraine  it  could  not  have  been 
at  any  time  previous.  Its  motion  at  the  time  of  the  deposition  of  the 
moraine  was  a  continuation  of  the  motion  it  had  had  previously  and  con- 
tinuously. The  situation  of  the  place  was  here  favorable  to  the  continuance 
of  the  flow  up  to  the  last. 

Three  inferences  are  indicated.  1.  The  Waldoboro  system  of  discon- 
tinuous gravels  was  formed  while  the  ice  was  in  motion.  2.  The  osar 
beneath  the  moraine  proves  that  the  thin  ice  of  that  time  (less  than  200 
feet  in  thickness)  could  flow  over  gravel  ridges  or  domes  without  pushing 
them  forward.  3.  This  gravel  was  probably  deposited  in  a  subglacial 
channel. 

In  the  valley  of  Georges  River,  and  also  near  Belfast,  we  find  several 
discontinuous  systems  of  gravels.  In  these  localities  the  direction  of  the 
ice  flow  during  the  last  part  of  the  Grlacial  period  was  many  degrees  different 
from  the  earlier  flow,  as  is  conclusively  proved  by  two  or  more  series  of 
glacial  scratches.  The  systems  of  lenticular  eskers  follow  the  direction  of 
the  scratches  last  made.  They  date,  then,  from  a  late  period,  when  the  ice 
could  no  longer  flow  over  the  higher  lulls,  but  was  forced  to  flow  around 
them. 

The  fact  that  the  series  of  lenticular  eskers  are  so  nearly  parallel  with 
the  direction  of  ice  flow  favors  the  hypothesis  that  they  were  formed 
beneath  the  ice  by  subglacial  streams.  In  several  places,  as  near  Union, 
the  surface  layers  of  the  northern  sides  of  the  lenticular  gravel  hills  are 
ci'umpled  and  distorted,  while  beneath  these  layers  the  stratification  is,  in 
the  cases  observed,  perfect.  Such  surface  distortion  might  result  from  the 
direct  pressure  of  ice  flowing  over  the  gTavel  hillock,  or  it  may  be  due  to 
the  settling  of  gravel  deposited  over  ice.  Thus  it  is  possible  that  pieces  of 
ice  containing  morainal  matter  may  break  away  from  the  roofs  of  tunnels 
and  be  rolled  along  for  a  time  like  stones.  If  such  were  deposited  as  a 
part  of  a  mass  of  glacial  gravel,  the  melting  of  the  ice  subsequently  would 


LENTICULAR  SHAPE  OF  COASTAL  GRAVEL  MASSES.  385 

distort  the  stratificatiou.  So  also  where  flowing  ice  abutted  against  a  sub- 
glacial  mass  of  gravel  it  mig-ht  often  do  so  unevenly,  so  that  cavities  of 
unequal  thickness  would  lie  between  the  ice  and  gravel.  Into  these,  if  new 
gravels  were  deposited,  the  subsequent  advance  or  melting  of  the  ice  would 
change  or  obliterate  the  stratification.  If  such  distortions  were  prevailingly 
on  the  stoss  side  of  the  gravel  hillocks,  as  they  were  in  the  places  examined, 
motion  of  the  ice  during  the  formation  of  the  gravel  deposit  would  be 
indicated,  and  also  subglacial  origin.  That  subglacial  streams  abounded 
near  the  coast  is  directly  proved  by  the  glacial  potholes,  also  by  the  pres- 
ence of  the  hunnnocks  of  glacial  gravel  directly  beneath  the  Waldoboro 
moraine,  and  by  other  facts. 

The  general  inference  follows  that  the  lenticular  kames  were  formed 
beneath  the  ice  at  a  time  when  it  was  so  thin  that  it  was  forced  to  flow 
over  them  without  pushing  them  forward  and  incorporating  them  with  the 
till  of  the  terminal  moraine,  as  appears  to  have  been  the  case  at  the  g-reat 
outermost  terminal  moraines.  And  if  these  lenticular  masses  were  formed 
beneath  flowing  ice,  their  shapes  must  be  due  in  part  to  the  same  forces 
that  produced  the  lenticular  hills  of  till.  Like  the  latter,  the  surfaces  of 
the  gravels  were  molded  into  the  forms  of  stability  by  the  ice  as  it  flowed 
over  them.  But  in  the  case  of  the  drumlin  the  ice  pressure  was  a  com- 
paratively constant  quantity,  while  in  the  esker  the  action  of  the  water  in 
melting  and  eroding  the  ice  was  a  controlling  agency  to  change  the  pres- 
sure and  in  part  to  mold  the  form.  The  ice,  as  it  advanced,  found  the 
head  of  its  columns  literally  melting  away,  so  that  if  the  supply  of  water 
continued,  the  enlai'gement  of  the  channel  might  often  jDroceed  even  more 
rapidly  than  the  advance  of  the  ice.  During  the  summer  time  if  these 
lenticular  gravel  hills  were  formed  at  the  base  of  "glacier  mills,"  it  is 
doubtful  if  the  ice  could  advance  so  fast  as  to  impinge  against  the  kame. 
But  during  the  winter,  when  the  supply  of  water  was  small  and  almost 
all  of  it  ice  cold,  the  amount  of  melting  and  erosion  would  be  greatly 
reduced.  Now  and  then  the  ice  would  abut  against  the  gravel  and  be 
forced  to  flow  over  it,  at  the  same  time  helping  to  carve  it  into  the  len- 
ticular form.  Indirectly  the  flow  of  the  water  in  the  space  between  the 
gravel  and  the  ice  of  the  glacier — a  space  caused  by  the  gradual  melting 
and  ei'osion  of  the  advancing  ice — would  tend  to  the  broadly  arched  form 
of  gravels.  Yet  since  the  water  would  erode  and  melt  the  ice  somewhat 
MON  xxxiv 25 


386  GLACIAL  GRAVELS  OF  MAINE. 

in-egularly,  we  can  not  expect  the  gravels  to  be  so  symmetrical  in  shape  as 
the  drumlins. 

The  lenticular  eskers  or  osars,  then,  have  the  natural  form  that  a  short 
mass  of  gravel  takes  when  formed  beneath  flowing  ice.  This  hypothesis 
assumes  that  the  present  deposits  were  stationary  and  the  ice  flowed  over 
them.  It  is  barely  possible  that  a  glacial  waterfall  where  a  surface  stream 
falls  down  a  creA^asse  may  foi'm  a  series  of  enlargements  at  intervals,  and 
that  these  enlargements  may  be  pushed  bodily  forward  with  their  con- 
tinued gravels.  This  would  imply  thick  ice  and  small  masses  of  gravel. 
At  the  time  the  present  lenses  were  formed  the  ice  could  not  push  forward 
the  graA^els,  but,  as  at  Winslows  Mills,  flowed  over  them,  only  now  and 
then  distorting  the  stratification  on  the  stoss  sides.  The  question  whether 
the  continuous  ridges  began  as  a  series  of  separated  lenses  which  at  last 
became  confluent  will  be  referred  to  later. 

DECREASE    OF    GLACIAL    GRAVELS    TOWARD    THE    COAST. 

As  has  already  been  repeatedl}-  stated,  the  maximum  development  of 
the  coarser  glacial  sediments  occurs  near  the  highest  sea  level,  which  in  the 
coast  region  is  not  far  from  the  contour  of  230  feet. 

Among  the  causes  of  great  precipitation  at  this  elevation  may  be  men- 
tioned the  following : 

1.  The  length  of  time  the  sea  stood  near  that  elevation.  That  the 
changes  of  level  of  the  sea  with  respect  to  the  land  were  geologically  rapid 
is  proved  by  the  fact  that  the  till  was  only  partially  eroded  over  the  sub- 
merged area.  I  have  found  no  cliff's  of  eroKsion  in  the  rock,  and  thus  have 
no  proof  of  long  pauses  in  either  the  advance  or  the  retreat,  and  therefore 
assume  that  the  rise  and  fall  of  the  sea  were  somewhat  uniform  in  rate.  If 
so,  it  follows  that  it  stood  near  its  highest  level  for  a  longer  time  than  at 
any  other — that  is,  during  the  last  part  of  the  period  of  advance,  the  time  of 
stationary  level,  and  the  earlier  part  of  the  retreat.  During  this  period  the 
modern  rivers  began  to  flow  and  form  deltas  off"  the  shore  of  that  time. 
Thus  a  vast  quantity  of  sediment  was  stopped  near  the  highest  shore-line. 
It  could  not  reach  farther  south  because  checked  in  its  motion  soon  after 
entering  the  sea. 

2.  The  effect  of  steeper  land  slopes  north  of  the  contour  of  230  feet. 
By  a  coincidence  the  slopes  of  the  laud  are  steeper  to  the  north  of  the 


GLACIAL  GKAYELS  OF  COASTAL  EEGION.  387 

230-foot  contour  over  large  parts  of  the  State.  The  steeper  slopes  were  areas 
of  greater  than  average  denudation  by  glacial  rivers,  and  the  more  level 
plains  were  areas  of  accumulation.  The  marine  deltas  of  York  and  Cum- 
berland counties  pass  upward  into  great  tracts  of  reticulated  ridges  that 
rise  to  450  or  500  feet  in  a  few  of  the  valleys,  but  the  deltas  in  that  part 
of  the  State  are  at  230  to  250  feet.  Obviously  the  proximity  of  the  change 
in  slopes  with  the  old  shore  line  is  a  mere  coincidence. 

3.  Possibly  a  more  rapid  rate  of  melting.  The  lower  marine  clays  are 
blue  to  black  in  color  and  are  very  fine  grained  and  often  richly  fossiliferous. 
The  later  marine  clays  pass  upward  as  the  basal  clays  of  the  valleys,  they 
are  lighter  in  color,  they  seldom  contain  fossils,  and  in  general  they  are  a 
little  coarser  grained.  Evidently  quiet  conditions  prevailed  for  a  time  after 
the  ocean  advanced  and  animal  life  flourished.  Later  the  conditions  were 
unfavorable.  If  due  in  jDart  to  the  great  inflow  of  fresh  water,  this  proves 
more  abundant  fresh  -^^'aters.  If  due  to  the  muddiness  of  the  water,  the 
streams  must  have  been  rapid,  which  could  be  accounted  for  by  increase  in 
the  size  of  the  streams  or  by  steeper  land  slopes.  Apparently  the  reeleva- 
tion  of  the  land  took  place  after  the  upper  marine  clays  were  deposited. 
The  advance  of  the  sea  over  considerable  portions  of  the  land  ought  to  have 
helped  to  ameliorate  the  climate  at  the  time  it  stood  at  its  highest  level 
irrespective  of  other  conditions.  On  the  whole,  we  conclude  that  while  it  is 
not  positively  proved  that  there  was  any  marked  increase  in  the  flow  of 
fresh  waters  into  the  sea  at  the  time  it  stood  at  its  highest  level,  yet  this  is 
probable. 

The  above-cited  causes  help  to  account  for  a  large  development  of  the 
glacial  sediments  at  or  near  the  highest  shore-line.  In  comparing  the 
gravels  at  this  elevation  with  those  found  near  the  present  shore,  we  are 
confronted  by  an  important  question:  Did  the  ice  retreat  from  the  coast 
region  before  the  advance  of  the  sea  1 

If  this  had  happened,  we  ought  in  that  region  to  find  overwash  gravels 
and  terminal  kames,  such  as  naturally  mark  the  recession  of  ice  on  the 
laud  A  good  place  to  look  for  such  gravels  is  at  the  Waldoboro  terminal 
moraine.  It  is  6  miles  long  and  crosses  two  valleys  favorable  to  the  forma- 
tion of  overwash  aprons.  At  the  road  from  Waldoboro  to  North  Waldoboro 
are  a  few  bars  of  subangular  gra^^el  that  probably  are  an  overwash  deposit 
made  while  the  moraine  was  being  formed.     If  there  is  any  other  overwash 


388  GLACIi^L  GRAVELS  OF  MAINE. 

matter  it  is  thin  and  covered  by  the  marine  clays.  I  found  none  exposed 
in  the  banks  of  the  Medomac  River,  though  the  discontinuous  osar  gravels 
are  easily  traced. 

Frontal  gravels  ought  especially  to  be  abundant  in  the  valleys  of  the 
larger  streams,  such  as  the  Penobscot  and  Kennebec,  if  the  ice  melted  over 
them  before  the  rise  of  the  sea,  and  we  do  not  find  them.  On  the  contrary, 
they  do  not  either  of  them  show  even  a  marine  delta  near  the  rivers,  though 
there  are  a  few  situated  a  few  miles  back  from  the  rivers. 

The'  conclusion  follows  that  the  ice  had  not  melted  over  the  coast 
region  previous  to  the  rise  of  the  sea  over  this  area.  The  retreat  of  the  ice 
front  was  accompanied  by  the  advance  of  the  sea,  if  not  in  part  caused  by  it. 

A  related  question  refers  to  the  earliest  glacial  sediments  of  the  ice- 
sheets.  As  before  noted,  the  ice  front  during  the  time  of  thickest  ice  must 
have  been  far  out  in  the  present  Gulf  of  Maine.  While  a  part  of  the  wast- 
age then  took  the  form  of  berg  discharge,  yet  there  must  have  been  sub- 
glacial  rivers  which  deposited  more  or  less  glacial  sediment  near  the  ice 
front.  We  do  not  know  what  development  these  gravels  took,  or  how  far 
they  were  incorporated  with  moraines  and  berg  droppings,  nor  do  we  know 
the  extreme  depth  beneath  the  sea  to  which  a  subglacial  stream  can  pene- 
trate and  retain  sufficient  velocity  to  transport  sediment.  Omitting  details, 
we  can  at  least  affirm  that  the  earliest  glacial  gravels  are  now  under  the  ocean. 

What  is  the  date  of  the  earliest  gravels  now  exposed  on  the  land?  As 
elsewhere  stated  more  fully,  in  the  coast  region  there  are  several  places 
where  the  glacial  gravel  systems  follow  the  scratches  last  made  when  the 
ice  was  deflected  by  hills  and  therefore  much  reduced  in  thickness  from  the 
maximum.  These  reach  as  far  southward  as  any  of  the  systems  except 
the  great  ones  that  come  to  Portland,  Jonesport,  and  Columbia,  and  appear 
to  be  as  old  as  any,  with  perhaps  these  exceptions.  This  gives  field  support 
to  what  we  should  expect  from  general  considerations — that  the  osars  were 
not  deposited  till  the  later  days  of  the  ice-sheet. 

In  comparing  the  quantity  of  the  coast  gravels  with  those  of  the  inte- 
rior, we  have  to  consider  ^the  effect  of  the  position  of  the  neve  line  at  various 
periods  of  the  ice-sheet's  history.  I  conceive  that  only  under  extraordinary 
conditions  is  the  n4y^  line  stationary  during  periods  of  the  advance  and 
the  retreat  of  the  ice  front.  It  is  perhaps  possible  that  there  can  be  such  a 
balance  of  circumstances — such  as  length  of  the  glacier,  surface  gradients, 


GLACIAL  GRAVELS  OF  COASTAL  REGION.  389 

rates  of  precipitation,  changes  in  seasonal  temperature,  and  other  chmatic 
conditions — that  a  glacier  can  grow  thinner  and  finally  disappear  without 
change  in  the  horizontal  position  of  the  n^ve  border.  But  in  the  case  of  a 
great  ice-sheet,  subject  to  other  than  local  conditions,  it  seems  to  be  highly 
jjrobable  that  there  was  a  retrogression  of  the  ne^vci  border  comparable  with 
the  retreat  of  the  ice  front  itself  If  so,  there  must  have  been  a  time  when 
the  area  of  the  zone  of  wastage  from  melting  attained  a  maximum  over 
Maine.  Previous  to  that  time  part  of  the  zone  of  wastage  had  extended 
southward,  where  the  ocean  now  is,  and  took  the  form  of  iceberg  discharge. 
As  the  n^ve  border  retreated  north  the  area  of  wastage  by  melting  that  was 
over  the  land  broadened  till  the  time  when  the  outer  margin  had  retreated 
back  to  the  present  coast.  Whether  the  neve  border  of  the  ice  front  would 
retreat  the  faster  after  that  is  uncertain,  since  we  do  not  know  what  effect 
the  rising  sea  had  in  melting  the  ice  before  it.  Leaving  open  the  question 
as  to  when  the  area  of  the  zone  of  wastage  from  melting  over  Maine  was 
greatest,  we  can  at  least  conclude  that  so  rapid  a  decrease  in  the  quantity 
of  gravels  as  takes  place  within  30  miles  of  the  coast  could  not  have  been 
caused,  unless  in  small  measure,  by  changes  in  the  position  of  the  neve 
line.  This  may  have  had  some  effect,  but  it  seems  improbable  that  its 
effect  could  all  be  concentrated  within  so  narrow  a  belt  and  be  so  con- 
spicuous here  while  hardly  traceable  elsewhere. 

The  causes  above  stated  account  for  the  great  development  of  the 
gravels  near  the  highest  level  of  the  sea,  but  throw  only  partial  light  on 
the  causes  of  the  rapid  decrease  in  the  gravels  toward  the  coast.  The 
subject  is  so  closely  related  to  the  fact  that  as  the  gravels  become  scanty 
they  also  become  increasingly  discontinuous,  that  the  further  treatment  of 
the  subject  is  postponed  and  will  be  considered  in  connection  with  the  latter 
topic. 

SUMMARY. 

The  most  important  characteristics  of  the  glacial  sediments  of  the 
coast  region  are  the  following: 

1.  Most  of  the  systems  contain  one  or  more  marine  deltas  situated  at 
different  distances  from  the  coast.  These  deltas  are  interpolated  in  the  midst 
of  the  linear  series  of  glacial  gravels  that  were  deposited  within  ice  walls. 

2.  The  continuous  osars  and  osar  terraces  oi  the  interior  as  they 
appi-oach  the  coast  break  up  into  ridges  separated  by  intervals.     Toward 


390  GLACIAL  GEAVELS  OF  MAII^E. 

tlie  south  the  intervals  become  on  the  average  longer  and  the  ridges  shorter, 
till  the  latter  are  reduced  to  cones,  domes,  and  short  ridges  or  plains.  The 
deposits  continue  to  become  smaller,  and  the  systems  end  north  of  the  aver- 
age line  of  the  coast,  and  most  of  them  only  a  few  feet  above  it. 

3.  The  maximum  development  of  the  glacial  sediments  is  found  near 
the  contour  of  230  feet. 

4.  The  gravel  deposits  of  the  coast  region  usually  have  rather  gentle 
lateral  slopes  and  convex  summits,  and  as  a  class  they  may  be  referred  to 
the  lenticular  type  of  eskers. 

5.  The  other  characteristics  of  the  coast  gravels,  their  topographical 
relations,  etc.,  do  not  differ  materially  from  those  of  the  interior,  except  that 
in  certain  places  the  gravels  of  the  discontinuous  systems  or  the  discon- 
tinuous portions  of  the  osars  and  osar-plains  have  the  marked  characteristic 
of  appearing  on  the  tops  of  low  hills  (less  than  120  feet  high),  while  in  the 
intervening  valleys  gravels  are  seldom  found. 

The  above-named  facts  present  special  difficulties  of  interpretation.  It 
is  certain  that  some  of  the  gravels  were  deposited  in  the  open  sea,  others  in 
ice  channels,  but  we  have  to  determine,  if  possible,  whether  the  latter  were 
deposited  beneath  sea  level.  Observations  made  on  the  land  can  give  us  little 
help  in  studying  offshore  deposits;  and  we  are  haunted  in  our  investigation 
by  the  uncertainties  attending  the  determination  of  the  border  line  of  the 
n^ve.  We  are  able  to  point  out  certain  agencies  that  nmst  have  been 
engaged  in  the  work,  but  a  satisfactory  explanation  demands  a  quantitative 
estimate  of  their  relative  efficiency.  This  field  of  investigation  is  untrod- 
den as  the  n^ve  of  the  ice-sheet  itself,  and  my  views  have  not  infrequently 
changed  while  studying  the  subject.  It  seems  impossible  to  take  up  these 
questions  at  any  point  without  anticipating  later  discussions. 

RETREATAL    PHENOMENA. 

A  topic  germane  to  a  comparison  of  the  discontinuous  coastal  gravels 
with  those  of  the  interior  of  the  State  pertains  to  the  manner  of  retreat  of 
the  ice  over  a  country  so  diversified  by  hills  and  valleys  as  Maine  at  a  time 
when  a  considerable  part  of  the  State  lay  beneath  sea-level.  Thus,  if  the 
terminal  melting  was  either  more  or  less  rapid  where  the  ice  was  in  contact 
with  the  salt  water  than  where  it  was  above  the  sea,  the  retreatal  phenomena 
would  be  very  complex.     The  ice  of  the  drainage  basins  of  many  of  the 


EETREATAL  PHENOMENA.  391 

glacial  rivers  would  not  only  be  attacked  from  the  front  lengthwise  of  their 
courses,  but  often  might  be  cut  off  by  the  sea  penetrating  transverse  valleys 
and  thus  arresting  their  flow  at  some  point  many  miles  to  the  north  of  their 
previous  mouths.  Thus,  from  the  north  end  of  the  Georges  River  discon- 
tinuous osar  system  in  Searsmont  it  is  a  less  distance  eastward  to  Belfast 
Bay  than  southward  to  the  coast  at  Thomaston  or  St.  George. 

In  marking  the  lines  of  synchronous  retreat  of  the  ice  front  the  deposits 
we  have  to  depend  on  are,  first,  terminal  moraines;  second,  marine  glacial 
deltas;  third,  frontal  or  overwash  aprons  of  glacial  sediments.  There  are 
many  such  deposits  in  Maine,  but  unfortunately  they  are  several  or  many 
miles  apart  and  no  contemporaneous  deposits  connecting  them  have  as  yet 
been  recognized.  In  the  table  on  page  393  these  deposits  are  divided  into 
classes.  The  order  of  deposition  was  first  determined  for  each  glacial  river 
separately.  Of  two  neighboring  deltas  the  one  that  was  north  of  a  line 
passing  through  the  other  parallel  to  the  general  coast  line  was  assumed  to 
be  the  later  deposit.  This  assumption  is  unsafe,  but  is  the  best  practicable 
test  at  present.  Obviously  the  rate  of  retreat  of  the  ice  front  is  determined 
by  the  ratio  between  the  rate  of  terminal  melting  and  ice  flow.  Naturally 
the  symmetry  of  the  retreat  is  much  marred  in  a  hilly  country,  and  may  be 
still  more  in  a  country  where  the  deeper  valleys  for  100  m'iles  or  more  from 
the  coast  were  beneath  sea  level.  If  the  ice  melted  more  rapidly  before 
the  advancing  sea  than  on  the  land  above  sea  level,  then  long  bays  on  the 
fiords  of  the  sea  would  deeply  penetrate  the  border  of  the  ice;  if  slower, 
there  would  be  formed  lobes  of  the  ice  reaching  as  capes  into  the  sea.  Thus 
the  long  Penobscot  and  Kennebec  valleys  were  at  that  time  below  sea  level 
for  more  than  100  miles.  Their  general  trend  is  nearly  parallel  with  that 
of  the  ice  flow,  and  both  open  northward  into  numerous  tributary  valleys. 
They  were  thus  favorably  situated  for  a  rapid  rate  of  ice  flow. 

Tw^o  glacial  rivers  flowed  from  the  Penobscot  Valley  eastward  through 
low  passes  into  the  valley  of  Union  River,  where  they  deposited  large 
marine  deltas  that  demand  considerable  time  for  their  deposition.  One  of 
these  overflows  was  from  Clifton  to  Otis,  the  other  from  Greenfield  to 
Aurora.  Manifestly  in  both  cases  the  ice  lingered  in  the  Penobscot  Valley 
all  the  time  they  were  forming,  while  the  open  sea  prevailed  over  the  valley 
of  Union  River.  Both  glacial  rivers  departed  from  places  in  the  Penobscot 
Valley  that  were  considerably  below  the  highest  sea  level.     The  distance 


392  GLACIA.L  GRAVELS  OF  MAINE. 

from  Clifton  to  Penobscot  Bay  is  about  the  same  as  from  Otis  to  the  mouth 
of  the  Union  River.  If  the  sea  that  rose  on  the  land  was  so  warm  that  the 
ice  melted  before  it  as  fast  or  almost  as  fast  as  the  sea  rose,  then  the  ice 
would  have  retreated  in  the  Penobscot  Valley  to  Clifton  as  soon  or  nearly 
as  soon  as  it  retreated  to  Otis  in  the  other  valley.  This  would  arrest  the 
flow  eastAvard  of  the  glacial  river.  If  any  delta  formed  in  Otis  it  would 
have  been  very  small  instead  of  large,  as  it  really  is.  The  same  reasoning 
applies  to  the  overflow  to  Aurora. 

Several  inferences  follow.  Although  the  sea  was  deeper  in  the  Penob- 
scot Valley,  yet  the  retreat  of  the  ice  was  relatively  slower  in  this  valley 
than  in  that  of  Union  River.  Part  of  this  diff'erence  may  be  due  to  the 
southeastward  motion  of  the  ice,  but  in  any  case  we  know  that  the  ice 
could  flow  into  regions  below  sea  level  and  maintain  itself  for  a  considerable 
time.  The  sea  was  cold,  and  ice  in  it  melted  slowly.  Comparing  two  val- 
leys, both  beneath  the  sea  level  of  that  time,  the  one  most  favorably  situ- 
ated for  a  rapid  flow  of  the  ice  showed  a  slower  rate  of  retreat  than  the 
other,  where  the  flow  of  the  ice  from  the  north  was  embarrassed  by  trans- 
verse hills. 

Elsewhere  are  described  the  glacial  lakes  that  were  formed  near  Lead 
Mountain,  Beddington.  These  were  formed  in  level  grounds  south  of  hills 
that  would  early  arrest  the  flow  of  ice  from  the  north.  For  many  miles  the 
glacial  river  that  deposited  g-ravels  in  these  lakes  flowed  a  half  mile  or  more 
west  of  the  Narraguagus  River  and  on  ground  50  to  100  or  more  feet  above 
it.  During  all  the  time  the  glacial  river  was  flowing  into  the  lakes  the 
deeper  river  A'alley  was  filled  Avith  solid  ice  to  a  point  south  of  the  lakes  at 
least.  In  other  words,  the  ice  in  lee  of  hills  melted  sooner  than  the  ice 
in  the  adjacent  north-and-south  A-alley  favorable  to  a  rapid  flow  from  the 
north.     This  happened  above  the  highest  sea  le^'el. 

Thus  both  above  and  beneath  the  sea  we  have  proof  of  a  lobate  front 
during  the  retreat  of  the  ice,  but  thus  far  no  definite  means  of  comparing 
the  relative  rates  of  retreat  in  the  two  cases. 

The  lines  of  synchronal  retreat  were  drawn  on  the  map  (PL  XXXI) 
to  connect  deposits  independently  determined  to  belong  to  approximately 
the  same  stages  of  retreat,  as  set  forth  in  detail  in  the  table.  When  the 
given  points  are  so  few  it  is  manifestl}^  impossible  to  exhibit  the  narrower 
sinuses  and  lobes  that  probably  marked  the  actual  lines  of  retreat. 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XXXI 


SYNCHRONOUS  GLACIAL  DEPOSITS. 


393 


The  following  list  gives  the  data  on  which  the  lines  were  drawn  on  the 
map.     It  must  be  considered  as  tentative,  not  final. 


List  of  approximately  synchronous  glacial  deposits. 


Localities. 

Kind  of  deposit. 

FIRST  .SERIES. 

Terminal  moraine. 

Gravel  massives,  apparently 

passing  into  the  sea. 
Delta. 

Terminal  moraine. 
Delta. 
Do. 

Jonesboro  tiud  .Jouesport 

Lamoine 

Waldoboro 

Korth  part  of  Alna 

Steveus  Plain,  Deering 

SECOND   SERIES. 

Meddy  bemps-Dennysville 

Old  Stream  Plains,  in  part 

Mont  Eagle  Plains 

Deblois  and  vicinity 

Delta. 

Do. 

Do. 

Do. 
Deltas. 
Delta. 

Do. 
Deltas. 
Delta. 

Do. 

Do. 

Do. 

Do. 
Deltas  and  gravel  massives. 

North  Searsraont,  Liberty,  and  Appletou 

Windsor 

Litchfield  Plain 

Gorham  and  North  Scarboro 

THIRD   SERIES. 

Cody  ville 

Old  Stream  Plains 

Marine  glacial  delta. 
Delta. 

Do. 

Do. 
Deltas. 
Delta. 

Terminal  moraine. 
Delta. 

Do. 

Greenbush,  Greenfield,  and  Milford 

Standish-Limingtou 

FOURTH    SERIES. 

Orneville-La  Grange  

Delta? 

Valley    drift     and     marine 

beds. 
Terminal  moraine. 

Harmony,  valley  of  Half  Moon  Stream 

Eeadfield 

394 


GLACIAL  GRAVELS  OF  MAINE. 


List  of  appro.cimatehi  si/nchronoiis  glacial  deposits — Continued. 


Kind  uf  deposit. 


Curtis  Corner,  Leeds Delta 


Turner- North  Auburn 

Poland  Corner 

FIFTH    .SERIES. 

Baldwin  iind  .Saco  Valley 

South  Paris 

Sumner  and  Buckfield 

Livetmore  and  Jay 

Cornville 


Canaan  

Dexter  and  Corinna 


SIXTH    SERIES. 


AYQodstocb,     Paris,     Hartford,     .Jay,    Mount 
Vernon,  Maytield,  Kingsbury,  etc. 


SEVBNTl-I    SFjRIES. 


Conway  ?- 


State  line,  Androscoggin  River 

Sunday,  Bear,  Ellis,  Swift,  and  Wild  rivers. 

Upper  Sandy  River  Valley 

New  Portland 

Upper  Kennebec  Valley 

Blanchard,  Piscataquis  '^'^ alley 

Katahdiu  Iron  Works 

Seboois  River 


EIGHTH   SERIES. 

Urabagog  outlet 


Kennebago  Valley . 

Kibby  Stream 

ParlinPond? 

Leadbetter  Falls?  . 


Do. 
Do. 

Glacial  gravels  nii.xed  with 

frontal  over  wash. 
Valley   drift    passing    into 

marine  fluviatile  delta. 
Glacial  marine  deltas. 
Valley    drift    jiassing    into 

fluviatile  marine  deltas. 
Valley  drift  and   fluviatile 

marine  delta. 
Overwash  plain  and  delta  ? 
Valley   drift    passing    into 

marine  beds. 


Belt      of      short      hillside 
eskers. 

Terminal  moraine  and  over- 
wash  gravels. 

Do. 
Overwash. 

Do. 
Moraines  and  overwash. 
Overwash. 

Do. 
Moraines  and  overwash. 
Osars  and  overwash. 


Ridge  of  till,  probably  ter- 
minal moraine. 
Kames  and  overwash. 
Osar  and  overwash. 
Osar. 
Do. 


SYSTEMS  OF  DISCONTmUOUS  OSAES.  395 

CAUSES    OF    NONCONTINUOUS    SEDIMENTATION    WITHIN    ICE    CHANNELS. 

The  nature  of  the  phenomena  here  referred  to  can  best  be  understood 
by  consulting  the  descriptions  of  the  discontinuous  and  continuous  osars, 
also  of  the  osar  terraces.  They  are  briefly  set  forth  as  follows :  If  we  start 
from  a  point  30  or  40  miles  from  the  coast  and  go  southward,  we  find  the 
gravels  becoming  more  and  more  discontinuous  (and  correspondingly 
smaller  in  size),  and  almost  all  the  systems  end  a  short  distance  from  the 
shore  and  at  only  a  few  feet  above  tide  water.  That  gravel  systems  of 
varying  lengths  and  having  very  different  topographical  relations  should 
terminate  over  the  whole  coast  at  almost  the  same  level  is  a  remarkable 
fact  and  apparently  associated  with  the  feature  of  noncontinuity. 

Omitting  from  present  consideration  the  deltas  which  were  deposited 
in  the  sea  or  in  lakes  sufficiently  large,  relative  to  the  inflowing  glacial 
river,  to  permit  a  horizontal  classification  of  sediments  from  coarse  at  the 
proximal  to  the  finest  clay  and  rock  flour  at  the  distal  end,  we  confine  the 
inquiry  to  sediments  deposited  in  ice-bordered  channels  or  basins,  under 
such  conditions  that  the  finest  of  the  glacial  debris  was  carried  away  by 
the  glacial  rivers  and  only  the  coarser  left.  We  premise  that  each  of  the 
discontinuous  osar  systems,  as  well  as  the  discontinuous  portions  of  the 
osars,  was  dejDOsited  by  a  single  glacial  river.  The  question  then  resolves 
itself  into  this  :  How  can  a  glacial  river  systematicallv  deposit  sediments  at 
intervals  in  its  channel  and  the  intervals  increase  as  the  size  of  the  gravel 
'deposits  decreases? 

Noncontinuous  sedimentation  by  a  single  glacial  river  might  be  accom- 
plished in  three  ways :  First,  the  river  might  be  depositing  sediments  in  two 
or  more  separate  parts  of  its  channel  simultaneously,  the  intermediate  por- 
tions of  the  channel  being  at  the  same  time  areas  of  erosion  and  transpor- 
tation; second,  sedimentation  might  proceed  by  stages,  the  separated 
deposits  being  made  one  after  the  other,  each  one  being  finished  before  the 
next  of  the  series  was  begun;  third,  both  these  methods  might  be  in 
oj)eration  simultaneously  in  different  j^arts  of  the  same  glacial  river. 

Again,  part  of  the  physical  agencies  that  lead  to  noncontinuous  sedi- 
mentation may  be  operative  only  when  the  tunnels  of  the  subglacial 
streams  open  beneath  the  sea  or  other  body  of  water,  and  others  may 
depend  wholly  on  conditions  originating  within  the  glacier  itself  or  on  other 


396  GLACIAL  GRAVELS  OF  MAINE. 

conditions  independent  of  the  presence  of  a  body  of  water  rising-  above 
the  bottom  of  the  ice  at  its  distal  extremity. 

Moving  waters  drop  a  portion  of  their  load  of  sediments  when  their 
velocity  is  for  any  reason  diminished,  or  they  have  a  greater  component  of 
the  force  of  gravity  to  overcome,  provided  they  were  just  able  to  carry  the 
load. 

One  cause  of  a  reduced  velocity  of  current  is  the  enlargement  of  the 
channel.  Local  enlargements  of  the  tunnel  of  a  subglacial  stream,  result- 
ing in  a  localized  slowing  of  the  waters,  are  formed  at  the  bases  of  cre- 
vasses down  which  warmed  superficial  waters  pour.  They  may  also  form 
in  rapids  where  the  waters  rebound  upward  in  passing  over  rocks,  or  where 
they  fall  to  the  ground  again  and  spread  lateralh',  or  where  the  subglacial 
waters  rise  into  crevasses  or  onto  the  surface  because  of  insufficient  or 
clogged  outlets.  Perhaps  the  most  important  method  of  enlarging  narrow 
tunnels  into  lake  basins  is  that  whereby  a  large  superficial  stream  forms  a 
pool  or  lake  where  it  pours  down  its  shaft  into  a  subglacial  or  englacial 
tunnel.  Gradually  the  warmed  surface  waters  melt  a  large  shaft  and  ulti- 
mately forixL  a  pool.  If  from  time  to  time  the  outlet  became  clogged  or 
proved  insufficient,  so  that  the  pool  and  shaft  became  filled  with  water 
exposed  at  the  surface  to  the  sunlight,  the  melting  would  be  accelerated 
and  ultimately  a  lake  Avould  be  formed.  When  once  the  water  of  the  lake 
became  exposed  to  the  sun  for  a  large  part  of  the  time,  the  enlargement 
would  be  still  more  rapid.  A  lake  might  also  form  where,  on  account  of 
stoppage  of  the  subglacial  stream,  the  waters  rose  through  creA^asses  onto 
the  ice  and  absorbed  heat  from  the  sun  The  extension  of  a  subglacial 
stream  northward  incidental  to  the  thinning  of  the  ice  nught  cause  a  series 
of  new  crevasses  to  open  across  the  course  of  a  supei'ficial  stream  and  a 
corresponding  series  of  enlargements  at  their  bases.  In  these  and  other 
ways  we  can  account  for  local  enlargements  of  subglacial  tunnels  into  hol- 
low cones,  domes,  and  caves  of  various  shapes,  also  into  basins  open  above 
to  the  air,  the  impetuous  waters  acting  on  the  ice  both  by  mechanical 
erosion  and  by  melting. 

When  a  subglacial  stream  tunnel  passes  up  and  over  a  hill  or  opens  at 
the  ice  front  beneath  a  body  of  water,  some  special  phenomena  demand 
notice.  The  Avater  in  the  tunnel  below  the  top  of  the  hill  or  surface  of  the 
body  of  water  (making  allowance  for  the  difference  in  the  specific  gravity 


NONCONTINUOUS  SEDIMENTATION  O  ICE  CHANNELS.         397 

of  the  glacial  and  the  frontal  water)  is  in  equilibrium.  This  part  of  the 
tunnel  and  all  its  connecting  crevasses  are  permanantly  filled  with  water 
that  can  flow  only  when  there  is  an  effective  head  of  water  rising  above  or 
behind  it.  At  the  proximal  end  of  this  permanent  body  of  water  the 
streams  in  summer  flow  with  such  velocity  as  to  keep  their  channels  clear 
of  sediment,  but  during  the  fall  and  winter  the  small  streams  are  checked 
as  they  flow  into  the  body  of  permanent  water  and  deposit  their  sediments, 
probably  to  wash  it  away  during  the  next  flood.  A  rising  or  falling  sea  or 
frontal  lake  might  under  some  conditions  cause  the  deposition  of  a  series  of 
such  sediments  formed  at  the  successive  levels  of  the  subglacial  portions 
of  the  sea  or  lake. 

Among  the  conditions  of  retreat  in  presence  of  a  cold  sea  (the  depres- 
sion of  the  Chiegnecto  Peninsula  would  assist  in  maintaining  a  rather  cold 
sea  on  the  coast  of  Maine)  is  the  marginal  zone  of  submarine  ice.  When  a 
glacier  ends  in  a  warm  body  of  water,  the  ice  margin  overhangs;  but  when 
it  ends  in  a  cold  body  of  water,  and  especially  in  salt  water  that  can  be 
cooled  below  32°,  the  waves  erode  the  upper  ice  just  as  they  do  other 
rocks,  and  leave  cliff's  overhanging  the  surf,  while  there  is  left  a  shelf  of  ice 
passing  out  beneath  the  sea  and  from  time  to  time  breaking  off  in  blocks 
and  rising  to  the  surface.^  The  breadth  of  this  zone  of  submarine  ice 
would  be  increased  if  the  basal  ice  contained  a  considerable  quantity  of 
glacial  debris  and  thus  weighted  it  down,  so  as  to  prevent  it  from  rising  as 
bergs.  The  breadth  of  this  ice  would  increase  during  the  winter,  partly 
because  of  the  colder  sea  and  partly  on  account  of  the  violence  of  the 
winter  storms  in  eroding"  away  the  upper  part  of  the  ice.  In  summer  the 
ice  would  begin  to  melt  this  projecting  shelf,  and  under  favorable  circum- 
stances might  before  autumn  melt  it  all  away  and  even  cause  an  overhang 
of  the  upper  ice. 

If  crevasses  opened  from  the  subglacial  tunnels  upward  to  the  surface 
of  this  submarine  ice,  the  subglacial  streams  would  rise  in  the  crevasses  and 
escape  on  the  surface  of  the  sea,  partly  because  their  specific  gravity  is  less 
than  sea  water  and  partly  because  they  would  thus  meet  less  friction.  If 
so,  the  stream  would  drop  much  of  its  sediment  at  the  base  of  the  crevasse. 

Another  cause  of  the  diminished  velocity  of  the  subglacial  streams  is  a 

1  Russell,  Nat.  Geog.  Miig.,  vol.  3,  p.  101,  1892. 


398  GLACIAL  GRAVELS  OF  MAINE. 

differential  subsidence  of  the  land  whereby  the  proximal  extremity  of  the 
ice-sheet  is  more  dejjressed  than  the  distal.  This  effect  would  be  intensified 
if  it  was  accompanied  by  a  corresponding  rise  of  the  sea  to  diminish  the 
surface  gradient  of  the  waters  of  the  glacial  streams. 

In  addition  to  the  varying  velocities  of  current  that  favor  sedimenta- 
tion, we  also  must  reckon  with  friction  and  the  force  of  gravity.  Thus 
manifestly  the  slopes  of  the  bed  of  a  subglacial  stream  favor  sedimentation 
when  the  stream  leaves  a  steeper  down  slope  for  one  less  steep  or  for  an  up 
slope,  since  a  greater  component  of  the  force  of  gravity  is  to  be  overcome. 

Thus  far  in  our  discussion  we  have  assumed  the  ice  to  be  stationary. 
But  one  of  the  important  works  of  glacial  ice  is  to  push  forward  the  sedi- 
ments that  gather  in  subglacial  tunnels.  Thus,  in  the  Kettle  moraine  of 
Wisconsin  thei'e  are  many  stones  that  have  been  very  much  rounded  by 
water  action  and  subsequently  thrust  forward  and  incorporated  with  the 
other  morainal  matter.  The  same  phenomenon  is  seen  at  the  larger  termi- 
nal moraines  of  the  Rocky  Mountains.  When  the  rate  of  ice  flow  is  rapid 
and  the  larger  part  of  the  ddbris  is  superficial,  all  or  nearly  all  the  glacial 
gravel  is  brouglit  forward  to  the  front  of  the  ice,  partly  b}'  the  streams  and 
partly  by  ice  pushing-.  A  considerable  part  of  the  waterworn  matter  is  left 
as  a  part  of  the  moraine  in  most  cases.  Indeed,  it  is  difiicult  to  account  for 
gravels  being  deposited  in  transverse  tunnels,  or  in  the  transverse  portions 
of  tunnels,  without  being  pushed  forward,  while  the  ice  remains  deep  and 
the  flow  rapid.  It  is  equally  difficult  to  account  for  gravels  being  pushed 
forward  by  the  ice  that  were  deposited  in  long-itudinal  tunnels  of  uniform 
size.  Occasional  mounds  occupying-  caves  in  the  base  of  the  ice  might  be 
pushed  forward.  Such  pushing  would  probably  obliterate  the  stratification, 
but  the  floods  of  the  succeeding  summer  would  restratify  it,  and  at  the  last, 
when  the  ice  became  sufficiently  thin,  it  would  no  longer  be  able  to  thrust 
it  onward,  but  would  be  forced  to  flow  over  it,  or  at  the  most  could  only  dis- 
organize a  portion  of  the  mass  on  the  stoss  side.  In  like  manner  we  can 
account  in  part  for  the  failure  of  the  ice  to  push  forward  transverse  gravels 
at  a  time  of  stagnant  thin  ice  and  ratlier  i-apid  rate  of  enlargement  of  the 
subglacial  channels. 

When  we  come  to  apply  these  general  principles  to  the  problem  of  the 
coastal  gravels  of  Maine,  we  note,  first,  that  domes  and  cones  of  gravel  up 
to  one-eighth  or  even  one-fourth  of  a  mile  wide  were  left  on  the  tops  of  low 


NONCONTIGUOUS  SEDIMENTATION  IN  ICE  CHANNELS.  399 

hills,  some  of  them  -wholly  or  largely  composed  of  till.  Here  great  enlarge- 
ments of  the  glacial  channels  were  formed  in  places  favorable  to  the  pro- 
duction of  crevasses.  Both  to  the  north  and  south  of  these  local  deposits 
the  glacial  rivers  left  no  gravels,  often  for  a  considerable  distance.  On  the 
whole,  we  must  admit  tliat  the  local  situations  of  such  of  the  coastal 
gravels  as  cap  hills  are  favorable  to  local  enlargements  of  the  channels  of 
the  glacial  streams,  and  therefore  to  sedimentation.  The  slopes  of  the  hills 
up  which  much  of  this  sediment  must  have  been  transported  would  also  aid 
sedimentation,  In  other  cases  there  are  no  relief  forms  of  the  land  that  we 
can  connect  with  the  positions  of  the  discontinuous  gravel  masses.  Only 
in  part,  then,  have  we  field  evidence  that  gravels  were  deposited  at  places 
favorable  to  local  enlargements  of  the  stream  channels. 

What  effect  had  the  marginal  zone  of  submarine  ice  on  the  distribution 
of  the  gravels! 

As  elsewhere  noted,  one  of  the  mounds  of  the  discontinuous  Medomac 
Valley  system  of  gravels  lies  beneath  the  moraine  at  Winslows  Mills.  The 
material  of  this  mound  is  much  waterworn.  If  any  of  the  deposits  of 
much  worn  gravel  can  be  connected  with  the  marginal  submarine  ice,  it 
ought  to  be  this,  for  it  bears  a  definite  relation  to  the  ice  front  at  a  certain 
period.  The  opinion  is  justified  elsewhere  that  the  gravels  were  deposited 
and  the  glacial  stream  that  left  them  had  ceased  to  flow  before  the  ice  had 
retreated  to  the  position  of  the  moraine.  The  bars  of  subangular  gravel 
that  lie  in  front  of  the  moraine  at  the  road  from  Waldoboro  to  North 
Waldoboro  may  be  frontal  gravels,  or  possibly  they  were  deposited  in  the 
marginal  zone  of  submarine  ice  a  few  rods  in  front  of  the  moraine.  These 
gravels  are  only  a  very  little  worn  and  are  unique  in  character.  If  there 
were  any  gravels  deposited  in  the  submarine  ice,  they  would  probably  be 
more  like  these  than  like  the  more  rounded  gravels.  The  rather  steep  two- 
sided  ridges  that  form  the  terminal  moraines  in  the  coast  region  point  rather 
to  overhanging  ice  than  to  a  projecting  wedge  of  submarine  ice  as  border- 
ing the  margin  at  the  times  the  moraines  were  deposited.  At  other  times 
it  may  have  been  different. 

If  a  subglacial  river  dropped  its  coarser  sediment  as  it  went  up  through 
crevasses  in  the  submarine  ice,  it  ought  to  have  deposited  its  finer  sand  and 
clay  near  by  as  a  delta  or  overwash  apron.  Such  deposits  would  be  formed 
near  the  ice  margin,  for  we  can  not  admit  any  great  breadth  of  submarine 


400  GLACIAL  GKAVELS  OF  MAINE. 

ice.  They  would  be  retreatal,  capping  older  sediments,  and  but  rarely 
would  they  form  an  isolated  mass  by  themselves,  as  I  conceive. 

While  admitting  that  some  marginal  submarine  ice  probably  exists, 
and  that  it  might  act  in  the  manner  indicated,  I  have  found  no  certain 
field  evidence  of  this  form  of  ice  action. 

Wei'e  the  discontinuous  coastal  gravels  begun  as  a  series  of  subglacial 
tide-level  deposits  during  a  gradual  rising  of  the  seal 

The  answer  to  this  question  is  short  and  positive.  The  discontinuous 
systems  cross  valleys  and  hills  and  gently  rolling  ground.  North  of  the 
hills  the  water  in  the  stream  channels,  no  matter  whether  they  were  super- 
glacial  or  subglacial  streams,  would  be  dammed  by  the  hills  in  front.  The 
rising  of  the  sea  could  produce  no  effect  beneath  the  surface  of  this  glacial 
dam.  On  a  continuous  southern  slope  we  might  admit  as  a  possibility  a 
series  of  tide-level  deposits  as  inaugurating  sedimentation  at  intervals,  but 
by  no  means  on  the  north  sides  of  hills  in  confined  channels  in  the  ice. 
But  in  another  way  we  may  have  proof  of  the  action  of  the  subglacial  sea, 
if  we  may  so  term  the  body  of  glacial  water  that  filled  the  cavities  of  the 
ice-sheet  up  to  sea  level.  The  East  Machias  osar  shows  a  series  of  broad 
I'eticulated  ridges  at  the  highest  sea  level,  but  no  delta  proper.  In  Lagrange 
and  Orneville,  in  the  Penobscot  Valley,  and  in  Canaan  and  Cornville,  in  the 
Kennebec  Valley,  we  find  near  the  highest  sea  level  that  the  long  osars 
that  follow  these  valleys  for  50  miles  expand  into  plains  with  some  of  the 
characters  of  narrow  marine  deltas  and  also  of  the  broad  osar  terraces. 
Here  it  is  probable  that  these  plains  or  partial  deltas  were  formed  at  sea 
level,  but  at  some  distance  back  from  the  ice  front,  so  that  no  delta  proper 
could  be  formed.  If  so,  this  would  prove  that  enlargements  of  glacial 
channels  and  sedimentation  took  place  at  the  point  where  the  stream  flowed 
into  the  permanent  subglacial  and  submarine  body  of  water.  Such  deposits 
are,  however,  very  different  in  structure  from  the  discontinuous  gravels  of 
the  coast  region. 

In  thi-ee  instances  in  Maine  osars  are  conspiciiously  discontinuous  on 
level  ground  at  long  distances  from  the  coast.  The  first  instance  is  that 
of  the  Katahdin  osar  near  South  Lincoln;  the  second,  that  of  the  Moose- 
head  Lake  osar  in  Abbott,  Guilford,  Sangerville,  and  Dover;  the  third,  the 
Anson-Madison  osar  in  the  northwestern  pai-t  of  Anson.  In  all  these  cases 
the  discontinuous  deposits  are  below  the  highest  sea  level,  or  in  a  glacial 
lake.     A  similar  coincidence  occurs  in  central  New  York,  where  Mr.  Gr.  K. 


NONOONTIKUOLTS  8EUIMENTATION  IN  ICE  CHANNELS.  401 

Crilbert  and  others  have  described  a  frontal  glacial  lake.  At  one  time  it 
lay  between  the  ice  on  the  north  and  the  hills  on  the  south  and  overflowed 
the  Rome  divide  into  the  Mohawk  Valley.  A  delta  deposited  by  glacial 
streams  in  this  lake  is  found  in  Schroeppel,  Oswego  County,  and  extending 
southward  into  Clay,  Onondaga  County,  and  other  towns.  Over  most  of 
the  Ontario  slope  in  that  region  there  are  numerous  short  ridges  and 
mounds  of  glacial  gravel,  and  some  of  them  are  arranged  in  north-and-south 
lines,  suggestive  of  deposition  by  a  single  glacial  river.  Is  this  association 
of  discontinuous  deposits  in  the  course  of  a  single  glacial  stream,  not  only 
on  the  coast  of  Maine  but  elsewhei'e,  with  the  presence  of  a  body  of  water 
in  front  of  the  ice,  causal  or  only  accidental? 

Regarding  the  cases  of  discontinuous  gravels  in  Maine  at  long  distances 
from  the  coast,  the  problem  is  complicated  by  the  fact  that  in  two  or  three 
cases  there  were  other  causes  that  may  have  been  more  significant  than  the 
presence  of  the  frontal  body  of  water.  Thus,  in  Anson  we  are  onl}^  2  or 
3  miles  from  a  large  terminal  moraine,  and  the  gravels  may  have  formed 
near  the  ice  front  as  local  kames  rather  than  as  parts  of  the  original  osar, 
dating  from  a  time  when  the  ice  of  the  Carrabassett  Valley  practically 
formed  a  local  glacier.  The  conditions  in  Abbott  and  Gruilford  may  be 
very  similar. 

The  first  question  that  arises  in  this  discussion  pertains  to  the  effect  of 
the  presence  of  the  frontal  body  of  water  on  the  development  of  the  sub- 
glacial  tunnels.  We  have  seen  that  when  the  glacier  lies  partly  below  the 
level  of  the  frontal  water,  the  tunnels  and  the  connecting  crevasses  are  per- 
manentl}^  filled  with  glacial  waters  up  to  the  level  of  the  sea  or  frontal  lake. 
The  water  in  the  crevasses  would  soon  attain  a  temperature  of  32°  and  then 
float  above  the  somewhat  warmer  water  contained  in  the  tunnels  below 
them.  All  the  water  of  surface  melting  in  this  part  of  the  glacier  would 
fall  into  the  crevasses  and  become  mixed  with  the  water  already  occupying 
the  lower  parts  of  the  crevasses.  The  convection  currents  would  be  feeble, 
and  but  little  of  the  heat  brought  down  by  the  surface  waters  would  get 
down  into  the  subglacial  tunnels  and  be  available  for  enlarging  them. 
Only  where  the  larger  surface  streams  poured  into  crevasses  would  the 
surface  waters  carry  a  surplus  of  heat  into  the  subglacial  tunnels.  The 
.smaller  brooks  and  seeps  would  be  so  mixed  with  the  cold  waters  of  the  cre- 
vasses that  their  heat  would  be  expended  in  melting  the  ice  walls  of  the 

MON  XXXIV 26 


402  GLACIAL  GEAVELS  OF  .MAINE. 

crevasses  perhaps  some  hundred  feet  above  the  tunnels.  Thus  over  all 
those  parts  of  the  ice-sheet  where  the  basal  ice  was  submerged  in  the  sea 
but  little  of  the  water  of  local  melting  was  available  for  enlarging  the 
main  tunnels,  but  the  melting  was  diffused,  so  to  speak,  over  many  times 
as  great  an  ice  surface  as  where  the  water  could  pour  down  a  crevasse  and 
escape  at  once  along  the  tunnel,  as  happens  in  case  of  glaciers  not  flooded 
by  basal  waters.  The  net  result  would  be  that  in  the  parts  of  the  ice-sheet 
where  the  basal  ice  was  submerged  the  subglacial  tunnels  were  far  less 
enlarged  than  they  would  have  been  if  the  gently  warmed  surface  waters 
could  have  sunk  at  once  into  them.  It  is  uncertain  how  far  the  outward 
jDressure  of  deep  bodies  of  water  can  overcome  the  inward  flow  of  the 
walls  of  the  tunnels,  but  on  the  coast  of  Maine  the  depth  of  the  perma- 
nent water  in  the  crevasses  was  at  the  most  only  about  200  feet,  and  it  is 
improbable  that  siTch  a  pressure  would  perform  any  important  work.  But 
irrespective  of  any  possible  partial  collapse  of  tunnels  formed  on  the  land 
as  they  were  pushed  beneath  the  cold  sea,  we  can  at  least  infer  that  the 
tunnels  were  not  enlarged  commensurate  with  the  suppl}^  of  waters.  For 
there  was  as  much  water  of  surface  melting  here  as  elsewhere  on  the  gla- 
cier, but  it  could  not  help  to  enlarge  the  tunnels  so  much  as  that  above 
sea  level.  The  tunnels  naturally  were  inadequate  to  carry  off  the  water  of 
summer  melting  as  fast  as  it  fell  down  from  above  into  the  crevasses. 
Each  crevasse  became  filled  with  water  above  sea  level  and  formed  a  stand- 
pipe  to  the  main  tunnels.  A  great  hydi-aulic  "head"  of  water  was  the 
result,  but  could  never  be  greater  than  that  which  was  due  to  the  gradient 
of  the  ice  surface,  since  if  the  crevasses  filled  to  the  top  the  water  would 
then  overflow  on  the  ice.  The  result  was  a  high  velocity  of  the  streams  in 
their  narrow  channels  with  consequent  little  sedimentation,  and  that  only  of 
the  coarsest  matter  and  under  the  most  favorable  circumstances.  The  local 
effect  of  basal  waters  would  be  felt  by  stream  channels  lying  wholly  in  the 
submerged  area  as  well  as  by  those  originating  above  the  sea  and  pushed 
beneath  it. 

In  other  words,  the  normal  transfer  of  heat  by  surface  waters  to  the 
base  of  the  ice,  where  it  is  the  chief  cause  of  the  enlargement  of  the  sub- 
glacial  tunnels,  is  in  a  large  part  arrested  where  the  base  of  the  glacier  is 
submerged  to  any  considerable  depth,  and  the  heat  is  expended  in  melting 
ice  in  the  crevasses  far  above  the  tunnels. 


HISTORY  OF  THE  COASTAL  GRAVELS.  403 

In  a  minor  and  more  indirect  wa}^  the  noncontinuous  gravels  appear 
to  owe  their  pecuhar  development  to  the  presence  of  the  sea  in  front  of 
the  ice.  Under  any  admissible  sm'face  gradient  of  the  ice  the  presence  of 
200  or  more  feet  of  frontal  water  rising  above  the  base  of  the  ice  would 
arrest  the  flow  of  such  of  the  subglacial  streams  as  did  not  have  their 
sources  more  than  3  to  5  miles  back  from  the  front,  so  as  to  have  sufficient 
head  to  drive  them  after  the  rise  of  the  sea.  Several  of  the  shorter  dis- 
continuous systems  do  not  exceed  this  length.  In  '  such  cases  the  rising 
of  the  sea  would  cause  the  development  of  the  gravels  to  cease,  and  we 
would  now  find  them  in  that  stage  in  which  they  happened  to  be  when 
their  streams  were  arrested.  If  we  grant  that  the  sea  had  no  direct,  only 
a  modifying,  effect  in  causing  noncontinuous  sedimentation,  still  it  would 
be  a  not  unimportant  role  to  fossilize,  so  to  speak,  the  work  of  the  shorter 
glacial  rivers  at  a  particular  period  of  their  history  and  preserve  it  for  our 
ins^jection. 

Having  thus  set  forth  what  appear  to  be  the  more  important  agencies 
in  producing  noncontinuous  sedimentation,  it  remains  to  examine  them  in 
their  mutual  relations  and  thus  obtain  a  more  general  view  of  the  subject. 

RESUME:     HISTORT   OF   THE   COASTAL   GRAVELS. 

As  already  repeatedly  noted,  the  three  distinguishing  features  of  the 
discontinuous  coastal  gravels  are  their  rapid  decrease  in  size  toward  the 
coast,  their  occurrence  at  longer  and  longer  intervals,  and  their  termination 
a  short  distance  north  of  the  shore  and  at  only  a  few  feet  above  tide  water. 
The  three  phenomena  are  so  widely  associated  that  they  would  appear  to 
have  had,  in  respect  to  their  principal  causes,  a  common  origin. 

The  history  and  causation  of  the  coastal  glacial  sediments,  so  far  as 
now  appears,  were  probably  about  as  follows,  assuming  that  in  the  coastal 
region  of  Maine  most  of  the  glacial  sediments  were  deposited  by  subglacial 
streams : 

If  these  changes  were  observed  in  case  of  only  a  few  of  the  gravel 
systems  that  reach  nearest  the  coast,  one  here  and  there,  the  facts  would 
seem  to  indicate  local  causes.  But  when  gravel  systems  are  found  every 
few  miles  along  200  miles  of  coast,  all  of  them  exhibiting  the  first  two  of 
the  above-named  characteristics,  and  all  but  five  the  third,  we  are  forced  to 


404  GLACIAL  GRAVELS  OP  MAINE. 

look  for  agencies  operating  along  the  whole  coast.  Horizontally  these 
changes  take  place  within  a  zone  generally  not  exceeding  about  30  miles  in 
breadth,  but  sometimes,  especially  in  the  larger  north-and-south  valleys, 
exceeding  that  limit.  Some  of  the  systems  end  some  distance  back  from  the 
coast  in  marine  deltas,  and  such  are  not  here  included  among  the  coastal 
gravels  proper.  The  southern  ends  of  such  of  the  systems  as  reach  nearest 
the  coast  lie  approximately  at  or  near  the  northern  ends  of  the  bays  or 
fiords  of  the  coast.  Vertically  the  northern  ends  of  the  discontinuous  sys- 
tems are  found  at  elevations  from  50  up  to  350  feet;  their  southern  ends 
liave  elevations  rather  less  than  50  feet. 

The  existence  of  numbers  of  glacial  potholes  near  the  shore  proves  the 
presence  of  subglacial  streams  in  the  coastal  region  south  of  the  ends  of 
the  gravel  systems.  The  scantiness  or  absence  of  gravels  at  the  shore  by  no 
means  leads  to  an  inquiry  as  to  the  local  absence  or  feebleness  of  subglacial 
streams  near  the  sea.  The  problem  is  an  entirely  different  one:  How  did 
it  happen  that  at  nearly  the  same  elevation  all  but  five  of  the  glacial  rivers 
along  200  miles  of  coast  found  themselves  with  so  large  a  supply  of  water, 
as  compared  with  the  sizes  of  their  tunnels,  that  they  were  able  south  of 
that  line  to  sweep  their  tunnels  clear  of  sediments,  or  nearly  so,  while  above 
that  level  and  to  the  northward  they  left,  in  channels  within  the  ice,  sedi- 
ments that  rapidly  increase  in  quantity  and  continuity  for  30  miles  or  more"? 
These  changes  are  so  great  and  so  rapid  that  it  is  practically  a  revolution 
-we  have  to  account  for. 

Looking  at  the  rapid  transitions  as  we  go  north  and  south,  we  are 
reminded  that  the  zone  of  transition  is  approximately  parallel  with  the 
position  of  the  ice  front  during  the  retreat,  and  we  naturall}''  seek  for  the 
causes  of  these  phenomena  in  some  phase  of  the  ice-sheet's  structure  or 
behavior  consequent  on  its  final  melting  and  disappearance.  On  the  other 
hand,  when  we  look  at  the  great  diff'erences  between  the  osar  rivers  as  to 
size  and  length;  when  we  see  how  parallel  some  of  them  were  to  the  ice 
flow  while  others  were  for  long  distances  transverse;  how  some  flowed  in  a 
single  drainage  valley  of  the  land  while  others  spanned  several  such  ^^alleys; 
how  some  were  in  broad  north-and-south  valleys,  where  the  ice  flow  was 
faster,  while  others  were  south  of  transverse  hills,  where  the  flow  was  slower; 
and  yet  all  but  five  end  before  reaching  the  shore,  and  there  is  no  proof 
that  these  five  extend  far  beneath  the  sea ;   when  we  think  of  the  small  ver- 


HISTORY  OF  THE  COASTAL  GRAVELS.  405 

tical  differences  between  the  southern  terminations  of  the  gravels  left  by  so 
many  glacial  rivers,  having'  so  many  topographical  relations  and  scattered 
over  so  wide  an  area,  we  are  driven  to  seek  for  agencies  capable  of  actiiig 
horizontally  over  the  whole  coast  simultaneously.  In  view  of  the  great 
differences  between  the  glacial  rivei's,  also  of  the  lobal  ice  front  during  the 
retreat,  it  seems  improbable  that  there  was  any  agency  capable  of  thus 
widely  acting  so  nearly  parallel  to  the  surface  of  the  sea  except  the  sea 
itself 

What  conditions  of  the  ice-sheet  independent  of  the  sea  would  tend  to 
produce  such  a  development  as  is  shown  by  the  coastal  glacial  gravels! 

Little  or  no  permanent  accumulation  of  sediments  can  be  made  within 
small  subglacial  or  englacial  tunnels — small,  that  is,  compared  to  the  flow 
of  waters — because  of  the  great  velocity  of  the  streams  during  the  summer 
floods.  And  such  they  remain  while  the  ice  is  deep  and  the  rate  of  flow 
rapid.  Before  the  streams  have  time  greatly  to  enlarge  their  channels  new 
ice  advances  from  the  area  of  accumulation  and  the  ice  containing  the  tun- 
nels already  somewhat  enlarged  has  reached  the  front,  where  it  is  melted  or 
discharged  as  bergs.  Under  these  conditions  the  rapid  subglacial  streams 
transport  almost  all  their  sediments  to  near  the  front  of  the  ice  and  deposit 
them  as  marginal  kames  or  beyond  the  ice  as  overwash  aprons.  In  this 
they  are  often  assisted  by  the  pushing  of  the  ice.  On  rather  steep  down 
slopes,  especially  where  the  waters  are  collected  in  the  lower  parts  of  val- 
leys, these  conditions  prevail  throughout  the  whole  time  of  the  I'etreat, 
until  the  glacier  becomes  too  small  to  support  large  streams.  Thus  all  the 
lai'ger  glaciated  valleys  of  the  Rocky  Mountains  contain  retreatal  plains 
of  frontal  gravels  up  to  about  5  miles  from  their  sources.  The  gravels  of 
the  Androscoggin  River  from  Bethel  to  Gorham,  New  Hampshire,  and 
also  those  of  the  upper  Carrabassett  Valley  are  probably  in  part  of  this 
character. 

But  when  an  ice-sheet  covers  a  variety  of  surface,  such  as  plains  and 
gentle  down  slopes,  and  especially  adverse  slopes,  or  when  there  is  a  sub- 
sidence greater  toward  the  source  than  at  the  distal  extremity,  the  glacial 
streams  become  able  g-reatly  to  enlarge  their  channels  as  the  ice  grows 
thinner  and  by  deg'rees  stagnant,  and  are  no  longer  able  to  keep  them  free 
from  sediment.  The  process  of  sedimentation  begins  at  favorable  places  in 
the  channels,  such  as  local  enlargements,  or  where  obstructions  rise  on  the 


406  GLACIAL  GRAVELS  OF  MAINE. 

beds  of  the  streams,  such  as  rocks  or  low  hills.  At  first  these  places  are 
few  and  at  long  intervals,  but  as  the  channels  still  more  enlarge,  sedimen- 
tation occurs  at  shorter  intervals,  until  at  last  it  is  practically  continuous. 
A  deposit  once  formed  that  the  ice  can  not  push  forward  becomes  a  nucleus 
around  which  more  gravel  gathers.  The  resulting  narrowing  of  the 
channel  aids  in  its  further  enlargement,  and  thus  in  process,  of  time  very 
great  masses  are  collected.  The  causes  of  enlargements  of  the  channels 
have  already  been  noted. 

One  class  of  the  coastal  gravel  deposits  demands  special  attention. 
These  are  numerous  massive  mounds,  also  plains  up  to  5  or  10  miles  in 
length  and  half  as  broad.  They  often  contain  kettleholes,  but  their  glacial 
character  is  that  of  massiveness,  and  they  are  by  no  means  so  conspicu- 
ously ridged  as  the  plexus  of  reticulated  kames.  Often  the  kettlehole  is 
simply  a  depression  in  what  would  otherwise  be  a  mesa  or  plain  with  a 
rather  level  or  gently  undulating  surface.^ 

These  deposits  are  sometimes  bordered  in  part  by  hills,  against  which 
they  lie  like  terraces,  but  they  usually  end  in  bluffs,  rising  above  the 
adjacent  land.  They  were  evidently  formed  within  ice  walls  either  wholly 
or  in  part.  One  of  the  most  remarkable  of  these  bluffs  is  that  along  tlie 
top  of  which  the  base  line  of  the  Coast  and  Geodetic  Survey  was  measured 
in  Deblois  and  Columbia.  Now,  if  even  the  largest  of  the  glacial  rivers 
flowed  into  lakes  as  large  as  the  largest  of  these  plains,  they  would  have 
deposited  deltas  showing  a  horizontal  assortment  of  sediments  from  coarse  at 
the  proximal  to  fine  clay  and  rock  flour  at  the  distal  end.  Instead,  these 
plains  are  composed  of  rather  coarse  matter — sand,  gravel,  cobbles,  etc. — 
with  but  little  horizontal  classification.  Some  of  them  are  150  feet  in 
height  and  must  contain  10  to  15  square  miles  of  surface. 

The  absence  of  such  reticulated  ridges  as  are  found  at  the  proximal 
ends  of  the  moraine  deltas  proves  that  the  subglacial  rivers  did  not  flow 
into  very  large  open  bodies  of  water.  It  is  a  better  interpretation  that  a 
small  channel  or  lakelet  open  to  the  air  was  first  formed.  These  gradually 
enlarged  by  the  lateral  melting  of  their  walls,  partly  by  the  heat  of  the 
inflowing  waters,  but  most  rapidly  from  heat  directly  absorbed  from  the 
sun.     The  subglacial  and  perhaps  to  some  extent  the  superficial  streams 

'  See  the  descriptions  of  tlie  Portlaud,  Readfield-Brunswieli,  and  Standish-Buston  systems, 
also  of  the  gravels  of  Gorliam,  Charlotte,  Freeport,  Auburn,  Jonesboro,  Columbia,  and  Deblois. 


HISTORY  OF  THE  COASTAL  GRAVELS.  407 

brought  in  sediments  and  dropped  them  in  the  lake.  If  sedimentation 
proceeded  at  about  the  same  rate  as  the  enlargement  of  the  lake,  there 
would  never  be  a  space  between  the  central  bar  of  gravel  and  the  ice  walls 
wide  enough  to  permit  the  formation  of  a  delta,  but  the  finer  ddbris  would 
be  carried  away.  The  outlets  of  the  lakes  were  too  narrow  to  permit  the 
deposition  of  sediment  within  the  tunnel  until  another  enlargement  or  tlie 
sea  was  reached.  It  does  not  seem  probable  that  the  surface  waters  could 
take  down  beneath  the  ice  heat  enough  to  produce  the  larger  glacial  lakes. 
In  such  cases  we  must  postulate  lakes  open  to  the  air  and  absorbing  heat 
from  the  sun. 

It  is  not  meant  to  imply  that  in  all  cases  the  gravels  were  deposited  in 
the  central  parts  of  the  lakes.  The  essential  part  of  the  process  is  that  the 
size  and  velocity  of  the  streams  bear  such  a  ratio  to  the  size  of  the  lake 
that  the  streams  are  not  sufficiently  checked  to  permit  their  depositing  the 
finer  debris.  Elsewhere  are  described  the  gravels  of  northeastern  Mon- 
mouth, where  the  glacial  river  flowed  swiftly  across  the  middle  of  small 
glacial  lakes,  depositing  a  terrace  of  coarse  gravel  on  each  side  of  its  course 
and  leaving  a  central  ravine  to  mark  its  channel. 

Among  the  possible  causes  of  a  small  enlargement  of  the  subglacial 
tunnels  south  of  the  north  ends  of  the  bays  or  fiords  of  the  coast  (fiord 
line)  may  be  mentioned  an  increased  rate  of  ice  flow  at  that  line.  The 
fiords  continue  for  some  miles  beneath  the  ocean,  as  is  shown  by  the  Coast 
and  Geodetic  Survey  charts,  but  they  are  shallow,  and  on  the  whole  the 
sea  floor  is  less  uneven  than  the  land,  and  the  slope  southward  is  somewhat 
steeper  than  the  average  land  slopes  north  of  the  fiord  line.  We  seem, 
then,  to  have  a  right  to  assume  that,  near  the  shore,  after  the  ice  had  passed 
the  higher  obstructing  hills,  it  would  have  its  rate  of  motion  somewhat  accel- 
erated. Crevasses  due  to  tension  owing  to  the  more  rapid  flow  toward  the 
ice  front  would  be  here  more  abundant  than  northward,  while  those  due  to 
inequalities  of  the  land  would  be  rather  less  abundant.  On  the  whole,  the 
conditions  probably  favored  the  restriction  of  the  subglacial  channels,  but 
it  would  be  difficult  to  place  a  quantitative  estimate  on  this  agency. 

We  must  also  consider  the  possibility  that  the  retreat  of  the  ice  may 
have  been  at  very  unequal  rates,  and  that  the  gravels  formed  near  or  not 
far  back  from  the  ice  front  would  be  determined  in  part  at  least  by  these 
varying  conditions  of  retreat.     If  so,  we  might  find  corresponding  types  of 


408  GLACIAL  GRAVELS  OF  MAINE. 

development  of  the  glacial  gravels  in  belts  marking  certain  stages  of  the- 
retreat  snch  as  I  have  not  attempted  to  mark  on  the  map.  Thus  far  I  have 
found  only  two  such  stages — one  at  the  coast  above  described,  and  the 
other  the  overwash  aprons  deposited  in  valleys  above  sea  level.  While  it 
is  probable  that  the  osars  were  deposited  somewhat  recessively,  yet  the 
absence  of  well-marked  stages  traceable  in  the  different  systems,  except 
such  as  bear  a  relation  to  the  old  sea  level,  indicates  that  the  retreat  of  the 
ice  alone  was  insufficient  to  account  for  the  termination  of  so  many  gravel 
systems  at  nearly  the  same  elevation.  Besides,  where  the  zones  of  accu- 
mulation and  waste  were  so  wide  as  they  must  have  been  in  so  great  an 
ice-sheet,  it  seems  hardly  probable  that  retreatal  phenomena  would  take  the 
form  of  a  great  transition  within  so  narrow  a  belt  The  ice  must  have 
extended  30  miles  beyond  Mount  Desert  Island  at  the  time  it  flowed  over 
that  island  if  it  had  a  surface  gradient  of  50  feet  per  mile,  which  is  twice 
the  average  gradient  of  the  ice  surface  between  there  and  Mount  Katahdin.^ 
Without  allowing  for  berg  discharge,  the  ice  would  reach  60  miles  south  of 
the  coast,  and  perhaps  actually  reached  half  or  two-thirds  that  distance. 
The  coastal  gravels  'may  have  been  deposited  20  or  more  miles  from  the 
ice  front.  Under  these  conditions  it  will  require  direct  and  positive  evi- 
dence to  connect  the  peculiar  development  of  the  coastal  gravels  with  any 
marginal  phase  of  retreatal  action.  Various  modifications  of  the  hypothesis 
suggest  themselves,  such  as  a  coincidence  of  the  subsidence  of  the  St. 
Lawrence  Valley  with  the  close  of  the  period  of  deposition  of  the  coastal 
gravels,  whereby  the  flow  of  ice  from  Canada  over  the  St.  John  divide  was 
impeded  and  the  development  of  the  osars  of  the  interior  of  the  State 
became  more  perfect  than  that  of  the  coastal  gravels,  which  was  arrested 
while  in  the  earlier  stages,  etc. 

What  conditions  favorable  to  such  a  development  as  is  exhibited  by 
the  coastal  gravels  depended  on  the  sea? 

The  subsidence  of  the  land  beneath  sea  level,  especially  a  greater  sub- 
sidence toward  the  north,  would  destroy  part  of  the  effective  "head"  of  the 
subglacial  streams.  Most  of  the  discontinuous  osar  systems  lie  in  regions 
that  were  beneath  the  sea  throughout  their  whole  length.  The  absence  of 
marine  deltas  favors  the  conclusion  that  numbers  of  the  shorter  osar  rivers 

'Distance,  120  miles;  elevation  of  surface  at  Mount  Katahdin,  4,500  feet;  at  Green  Mountain,. 
Mount  Desert,  1,500  feet. 


LATE  GLACIAL  HISTORY  OP  THE  COASTAL  REGION.  409' 

ceased  to  flow  because  of  the  rise  of  the  sea  before  the  retreat  of  the  ice  as 
far  back  as  the  southern  terminations  of  the  gravel  systems — that  is,  their 
work  ceased  while  they  were  yet  in  the  early  or  discontinuous  stage  of  ice- 
channel  sedimentation.  It  is  uncei'tain  how  far  this  remark  applies  to  the 
longer  rivers  that  formed  no  marine  deltas. 

As  previously  pointed  out,  the  subsidence  of  the  ice-covered  land 
beneath  sea  level  would  cause  the  tunnels  and  lower  part  of  the  crevasses 
to  become  permanently  filled  with  water  at  32°.  The  manner  in  which 
these  basal  waters  tend  to  restrict  the  enlargement  of  the  subglacial  tunnels 
has  been  already  described  at  some  length.  Of  all  the  agencies  known  to 
me  for  the  production  of  the  coastal  gravels  and  their  limitations,  this 
appears  to  have  been  the  most  efficient. 

LATE  GliACIAIi  HISTORY  OF  THE  COASTAL  EEGIOjST. 

The  history  of  the  coastal  region  appears  to  have  been  about  as  follows: 
Without  assuming  any  definite  positions  for  the  southern  border  of  the 
area  of  accumulation  at  particular  periods  of  the  life  of  the  ice-sheet,  we 
may  confidently  affirm  that  during  the  time  of  maximum  glaciation  a  large 
part  of  the  zone  of  waste  was  south  of  the  present  shore  and  that  the  earlier 
kames  and  overwash  gravels  are  now  beneath  the  ocean.  At  the  time  when 
the  coastal  gravels  were  being  deposited  the  higher  hills  of  that  region  were 
able  to  deflect  the  ice  from  its  earlier  direction  of  movement.  The  height 
of  these  hills  limits  the  thickness  of  the  ice  of  this  period  to  not  much  if 
any  more  than  1,000  feet,  and  it  may  have  been  considerably  less.  On  the 
other  hand,  the  flow  of  the  osar  rivers  that  deposited  the  Medomac  Valley 
system  of  discontinuous  gravels  had  ceased  at  the  time  the  Waldoboro 
moraine  was  being  formed — that  is,  before  the  ice  had  become  less  than 
100  to  200  feet  in  depth.  The  coastal  gravels  date,  then,  from  the  time  just 
2Dreceding  the  retreat  of  the  ice  to  the  present  shore,  or  perhaps  to  the  north 
ends  of  the  fiords.  The  absence  of  frontal  gravels  from  the  coastal  region 
except  in  the  form  of  marine  deltas  proves  that  the  sea  beat  against  the 
front  of  the  ice,  or  at  least  against  its  base,  during  all  the  time  of  the 
retreat  up  to  the  highest  beach.  Some  of  the  marine  deltas  were  formed 
not  more  than  100  feet  above  the  present  sea  level  and  only  2  to  5  miles 
north  from  the  southern  ends  of  the  gravels  of  the  same  systems.  We 
infer  that  the  sea  had  i-eached  at  least  one-half  of  its  final  elevation  by  the 


410  GLACIAL  GRAVELS  OP  MAINE. 

time  the  ice  had  retreated  back  to  these  deltas — how  much  more  we  do 
not  know.  We  thus  reach  the  conchision  that  the  sea  was  somewhat  above 
its  present  level  at  the  time  the  coastal  gravels  were  deposited,  but  how 
much  is  not  yet  determined  by  the  gravels  themselves  in  their  development 
as  deltas. 

During  the  thinning  of  the  ice  the  subglacial  streams  were  extended 
farther  north  into  regions  before  drained  by  superficial  streams  which  were 
situated  far  up  on  the  glacier  and  extended  into  the  slush  zone  of  snow. 
None  of  the  basal  debris  could  get  up  so  high  above  the  ground  as  this, 
and  .only  Mount  Katahdin  has  been  supposed  to  have  been  above  the  ice 
surface.  This  class  of  superglacial  streams  could  not  have  deposited  the 
coastal  or,  unless  rarely,  any  other  glacial  gravels.  The  class  of  superficial 
streams  that  form  near  the  ice  front  may  have  assisted  in  the  formation  of 
the  coastal  gravels,  as  at  the  marine  deltas,  the  glacial  lakes,  and  by  collect- 
ing sediment  which  they  poured  into  subglacial  tunnels.  No  matter  where 
the  ndvti  line  had  been  at  the  time  of  deepest  ice,  it  certainly  was  far  north  of 
the  shore  at  the  time  the  coastal  gravels  were  deposited,  for  this  was  well 
on  in  the  period  of  retreat.  As  the  n^v^  line  retreated  northward  and  the 
subglacial  di-ainage  was  correspondingly  extended,  the  time  came  when 
that  portion  of  the  ice-sheet  drained  by  subglacial  rivers  was  at  a  maxi- 
mum over  the  State.  Obviously  the  longer  a  glacial  river  is,  the  greater 
will  be  the  enlargement  of  its  channel,  other  things  being  equal.  The 
amount  of  water  passing  southward  at  the  shore  would  increase  so  long  as 
the  length  of  the  subglacial  streams  north  of  the  shore  was  increasing,  up 
to  the  time  of  the  retreat  of  the  ice  to  that  line,  if  the  sea  did  not  interfere 
with  the  development.  The  time  of  maximum  subglacial  drainage  surface 
probably  was  near  the  time  when  the  coastal  gravels  were  deposited,  or 
somewhat  later.  This  would  cause  a  large  flow  of  water,  but  not  a  large 
sedimeiitation,  except  where  tliere  was  a  corresponding  enlargement  of  the 
subglacial  channels.  For  a  time  the  base  of  the  ice  in  the  coastal  regions 
was  flooded  with  cold  waters  because  of  the  subsidence  beneath  the  sea, 
and  the  flow  of  the  ice  was  probabl}'-  more  rapid  south  of  the  fiord  line. 
These  and  other  physical  causes  so  far  prevented  enlargement  of  the  sub- 
glacial tunnels  in  the  coast  region  that  sedimentation  became  more  scanty 
and  at  longer  intervals  southward  and  finally  ceased  "near  the  fiord  line. 
-South  of  this  line,  in  all  except  a  few  instances,  the  glacial  rivers  were  so 


LATE  GLACIAL  HISTORY  OF  THE  COASTAL  EEGIOK  411 

large,  as  compared  with  the  capacity  of  the  tunnels,  that  they  were  able  to 
sweep  their  tunnels  clear  of  sediments,  or  nearly  so.  In  many  places  near 
the  coast  there  were  formed  at  this  period  glacial  lakes  too  large  to  be 
ascribed  to  melting  by  subglacial  waters  and  which  were  probably  open 
above  to  the  sun.  The  ice  could  have  been  only  a  few  hundred  feet  deep 
at  the  time  of  their  formation.  The}^  appear  to  have  been  formed  by 
gradual  enlargement  around  a  growing  plain  of  gravel.  Numerous  marine 
deltas  are  found  in  this  region,  sometimes  alternating  in  the  course  of  the 
same  gravel  system  with  the  massives  or  plains  deposited  in  the  glacial 
lakes,  which  massives  show  little  or  none  of  the  horizontal  assortment  of 
sediments  belonging  to  the  delta  deposited  in  still  water.  The  deltas  and 
terminal  moraines  mark  lines  of  retreat,  but  it  is  difficult  to  synchronize 
them. 

SUMMARY. 

The  waters  of  surface  melting  utilize  the  crevasses  of  the  glacier  for 
penetrating  to  the  bottom  of  the  ice  or  into  it,  where  they  force  a  passage 
along  the  crevasses  or  beneath  the  ice,  assisted  more  or  less  by  the  basal 
waters  and  furrows  in  the  base  of  the  ice. 

The  narrow  channels  due  to  fracture  or  the  crannies  which  the  waters 
open  by  their  pressure  are  enlarged  by  melting  and  mechanical  erosion  into 
tunnels  which  sometimes  expand  into  chambers,  caves,  and  channels  of 
various  shapes  and  sizes,  and  may  open  above  to  the  sunlight. 

Other  things  being  equal,  when  glaciers  lie  on  the  land  and  disappear 
by  melting  without  berg  discharge,  the  amount  of  enlargement  of  the 
tunnels  varies  directly  as  the  time  they  are  being  enlarged,  i.  e.,  inversely 
as  the  rate  of  ice  motion. 

The  enlargement  of  the  tunnels  is  antagonized  by  a  slow  inward  flow 
of  the  ice  walls.  The  laws  that  govern  the  rate  of  inward  flow,  how  far 
the  rate  is  determined  by  the  depth  of  ice  or  by  variations  of  pressure 
caused  by  the  ice  movement  over  obstacles  or  by  heat  transmitted  through 
the  ice,  etc.,  are  unknown. 

The  transfer  of  energy  beneath  the  glacier  by  gently  warmed  surface 
waters,  the  heat  of  which  is  generally  available  for  the  enlargement  of  the 
subglacial  or  englacial  tunnels  by  melting  their  walls,  is  greatly  hindered 
when  the  glacier  flows  into  a  body  of  water,  since,  as  the  warmed  waters 
pour  into  the  cold  waters  that  bathe  the  basal  ice,  they  become  more  or  less 


412  GLACIAL  GRAVELS  OF  MAINE. 

mixed  with  them,  and  thus  a  large  portion  of  the  heat  is  expended  in 
melting  ice  within  the  crevasses  and  not  within  the  tunnels. 

Other  things  being  equal,  surface  melting  is  independent  of  the  basal 
condition  of  the  ice,  i.  e.,  whether  the  ice  is  submerged  or  not.  In  other 
words,  the  flowing  of  a  glacier  down  into  a  body  of  water  prevents  the 
enlargement  of  the  subglacial  tunnels  to  the  full  sizes  they  would  have 
had  but  for  the  presence  of  the  water,  while  the  supply  of  surface  waters 
under  like  conditions  is  not  diminished. 

An  increased  supply  of  water  with  a  corresponding  enlargement  of  the 
outlets  implies  an  increase  in  the  velocity  of  flow,  hence  increased  trans- 
portation and  diminished  sedimentation. 

A  sudden  and  marked  decrease  in  sedimentation  at  or  near  a  certain 
contour  along  200  miles  of  coast  implies  some  agency  acting  horizontally 
over  a  wide  area  to  produce  an  increase  in  power  of  transportation  (with 
decrease  of  sedimentation)  below  that  level. 

In  Maine  we  have  such  a  transition  at  the  southern  ends  of  such  of 
the  gravel  systems  as  reach  nearest  the  coast,  and  thence  extending  for  a 
few  miles  northward.  In  general  there  are  topographical  conditions  favor- 
able to  a  somewhat  more  rapid  rate  of  ice  flow  south  of  this  line,  but  on  a 
somewhat  hilly  and  uneven  coast  this  cause  ought  to  result  in  differences 
in  the  elevations  of  the  southern  ends  of  the  gravel  systems.  Hence, 
while  it  is  probable  that  the  rate  of  ice  flow  was  accelerated  south  of  the 
northern  ends  of  the  fiords  (fiord  line),  it  could  have  been  only  a  contribu- 
tory rather  than  a  controlling  cause  of  the  relatively  small  enlargement  of 
the  subglacial  tunnels  south  of  the  fiord  line. 

The  ending  of  the  gravels  at  nearly  the  same  elevation  can  best  be 
accounted  for  by  supposing  the  basal  ice  to  have  been  submerged  in  the 
sea  to  an  unknown  depth  not  exceeding,  along  the  outer  coast  line,  about 
200  feet  below  the  highest  level  attained  by  the  sea. 

The  highest  beaches  along  the  outer  coast  have  nearly  the  same  eleva- 
tion above  the  present  sea  level.  This  is  independent  evidence  that  the 
surface  of  the  sea,  measured  northeast  and  southwest,  at  the  time  of  its 
greatest  elevation  was  approximately  parallel  to  its  present  shore,  with  per- 
haps a  little  local  warping  in  the  Penobscot  Valley  and  in  a  few  other 
places.  If  the  petering  out  of  the  gravels  near  the  fiord  line  was  largely 
the  result  of  basal  submergence  of  the  ice-sheet  in  the  sea,  the  termination 


OSAES.  413 

•of  the  gravels  at  their  southern  ends  so  near  the  same  horizontal  line  could 
have  been  predicted  and  is  just  what  it  ought  to  be  according  to  that 
hypothesis. 

There  is  independent  evidence  that  the  sea  beat  against  the  ice  front, 
or  at  least  against  its  base,  all  the  time  of  the  retreat  back  to  the  highest 
beaches.  This  proves  a  somewhat  higher  level  of  the  sea  during  the  time 
when  the  coastal  gravels  were  being  deposited,  and  is  presumptive  evidence 
•of  the  presence  of  the  sea  over  the  present  land  at  such  a  level  as  would 
then  submerge  the  basal  ice  at  the  fiord  line  and  account  for  the  revolution 
or  transition  in  the  development  of  the  glacial  sediments  that  took  place 
near  that  line. 

Thus,  from  whatever  point  of  view  we  approach  the  subject,  we  find 
the  development  of  the  coastal  gravels,  according  to  the  hypotheses  indi- 
cated, presenting  a  connected  and  self-consistent  series  of  phenomena.  If 
so,  a  corresponding  development  ought  to  be  found  wherever  glaciers  flowed 
into  the  sea  from  regions  where  the  conditions  were  such  that  continuous 
osars  formed  on  the  land.  Probably  the  presence  of  marginal  glacial  lakes 
of  fresh  water  also  helped  to  aiTest  the  enlargement  of  the  subglacial 
tunnels,  but  perhajjs  not  so  much  so  as  sea  water. 

So  complex  is  the  problem  that  it  can  not  be  claimed  that  all  the 
■elements  have  been  set  forth  above. 


The  long  continuous  ridges,  or  osars,  are  a  feature  of  the  interior  of 
the  State.  They  are  usually  continuous  for  only  a  few  miles  and  then  are 
interrupted  in  various  ways.  Where  they  go  up  and  over  hills  the  gravel 
is  usually  abundant  on  the  northern  slopes,  while  little  and  sometimes  no 
gravel  is  found  on  the  tops  of  the  hills,  especially  when  penetrating  narrow 
passes.  On  steep  southward  slopes  the  gravel  is  often  scanty  or  absent  for 
long  distances,  and  then  at  the  foot  of  the  slope  large  ridges  or  often  plains 
are  found.  Here  and  there  on  these  steep  southern  slopes  (20  to  80  feet 
per  mile)  may  be  found  small  masses  of  bowlderets  and  bowlders  that  are 
well  rounded  by  water.  These  as  truly  are  the  local  representatives  of  the 
osar  as  if  they  formed  a  large  ridge.  It  is  not  a  definite  amount  of  gravel 
that  is  necessary  to  form  an  osar  or  to  prove  where  the  glacial  river  ran. 
'The  above-named  gaps  in  the  osars  appear  to  have  a  direct  relation  of  effect 


414  GLACIAL  GEAVELS  OF  MAINE. 

and  cause  to  the  slopes  of  the  land.  But  gaps  are  not  seldom  found  m  the 
midst  of  a  level  plain,  which  we  can  not  attribute  to  conditions  of  the  land 
surface.  There  is  no  change  in  the  slopes,  nor  hills  to  produce  crevasses, 
nor  narrowing  of  valleys.  Such  gaps  must  have  been  2Droduced  wholly 
by  local  conditions  of  the  ice  and  glacial  streams.  Many  of  the  osars  have 
been  washed  away  by  streams,  but  such  breaks  in  the  ridges  are  not  con- 
sidered as  true  interruptions  of  the  system.  Erosion  gaps  were  made  sub- 
sequently to  the  formation  of  the  ridge,  an  accident  having  nothing  more 
to  do  with  the  original  form  of  deposition  than  if  the  gravel  had  been  drawn 
away  to  build  a  road.  The  osar  in  this  report  is  considered  "interrupted" 
only  when  for  some  reason  the  gravel  was  not  originally  deposited  continu- 
ously. These  gaps  are  so  short,  as  compared  with  the  long  reaches  of 
gravel,  that  on  the  State  maps  they  often  can  not  be  represented  without 
exaggeration.  When  mapped,  the  ridges  are  seen  to  have  a  linear  arrange- 
ment which  the  longest  of  the  gaps  do  not  obscure.  If  represented  on  a 
detailed  topographical  map,  the  close  connection  of  the  ridges  would  be  still 
more  clearly  indicated. 

The  ridges  formed  by  a  single  glacial  i-iver,  including  its  tributary  and 
delta  branches,  are  marked  as  a  single  system.  Osars  marked  as  tributary, 
can  be  traced  to  a  definite  junction  with  each  other  or  to  points  very  near 
each  other,  where  they  are  separated  by  intervals  no  greater  than  are  ordi- 
narily found  in  the  main  ridges  in  the  same  region  and  on  the  same  sort  of 
land  surface.  When  osars  approach  each  other  as  if  they  were  tributaries, 
but  instead  one  (or  both  of  them)  expands  into  a  delta  and  seems  to  end 
before  reaching  the  other,  they  are  regarded  as  distinct  systems  (e.  g., 
Pleasant  River  and  Lilly  Bay  systems). 

The  osar  sj^stems  are  of  various  lengths  up  to  130  or  140  miles. 
Briefly  summarized,  the  more  important  facts  are  as  follows:  Their  materials 
are  more  or  less  rounded,  polished,  and  assorted  by  flowing  water.  The 
water  flowed  along  the  ridge.  In  most  if  not  all  cases  it  flowed  southward, 
as  is  proved  by  the  direction  of  transportation,  by  the  dip  of  the  strata,  by  the 
positions  of  the  deltas,  and  by  the  fact  that  at  the  north  ends  of  the  sys- 
tems the  stones  are  usually  much  less  waterworn  than  at  the  south  ends. 
The  gravel  usually  rises  above  the  land  on  each  side.  These  phenomena, 
as  well  as  the  meanderings  of  the  systems,  could  be  produced  only  by 
rivers  flowing  between  solid  barriers  that  have  now  disappeared.    Ice  is  the 


w 


,Vl\. 


KV^*-^   ^    f '^  -^^^^^X 


A 


T^:^^  "^fr 


^> 


5     - 


OSARS.  415 

only  solid  that  can  have  served  this  purpose.  The  osar  rivers  had  tributary 
and  delta  branches  like  those  of  ordinary  rivers.  While  often  following 
drainage  slopes  like  surface  rivers,  yet  more  often  they  traversed  rolling 
plains  or  passed  over  hills  from  one  drainage  basin  to  another,  thus  freely 
disregarding  the  minor  inequalities  of  the  land.  In  only  a  few  cases  did 
they  cross  hills  risii:ig  more  than  200  feet  above  the  valleys  on  the  north. 
They  penetrate  the  hilly  regions  along  low  passes,  and  often  take  the  form 
of  terraces  far  up  on  the  hillsides. 

Several  features  of  the  osars  require  further  discussion.  The  osars 
proper  are  best  developed  in  central  and  eastern  Maine.  The  northern 
parts  of  the  longer  ridges  are  rather  small  and  narrow  and  have  rather 
steep  lateral  slopes.  Standing  on  the  narrow  top,  the  meandering  ridge 
often  presents  an  uneven,  heaped  appearance,  much  like  a  moraine.  Going 
southward,  on  the  average  the  ridges  become  larger  and  have  a  more  even 
surface.  When  within  about  75  miles  of  the  coast,  every  few  miles  enlarge- 
ments of  the  ridges  are  found  which  have  various  forms.  Sometimes  they 
are  little  tables  only  200  to  300  feet  wide  and  two  or  three  times  as  long. 
These  may  be  solid  or  may  contain  one  or  more  shallow  kettleholes.  Hei'e 
and  there  a  hummock  appears  on  top  of  the  osar,  rising  20  to  40  feet  above 
the  rest  of  the  ridge,  and  at  these  "pinnacles"  the  ridge  is  generally  broader 
than  elsewhere.  At  one  or  two  places  within  the  belt  of  country  lying 
between  50  and  75  miles  from  the  coast,  Ave  find  the  osar  usually  divides 
into  two  or  more  ridges  which  after  a  time  come  together  again  and  form  a 
sing'le  ridge.  They  thus  inclose  long,  narrow  basins,  or,  when  connected 
by  cross  ridges,  rather  deep  kettleholes.  These  areas  of  reticulated  ridges 
are  not  large,  a  mile  or  two  in  length  and  hardly  an  eighth  of  a  mile  wide. 
In  this  part  of  their  courses  several  of  the  osars  expand  into  broad,  solid 
plains  or  massives  a  mile  or  two  long  and  nearly  half  as  wide.  Thus,  in 
Grreenbush  the  Katahdin  system  twice  expands  into  massives  of  this  kind 
rising  about  100  feet  above  the  rest  of  the  osar  and  the  level  plain  in 
which  they  are  situated.  Their  surfaces  are  rolling  and  afford  some 
shallow  basins,  but  they  can  not  be  regarded  as  a  plexus  of  reticulated 
ridges  in  their  present  form.  They  are  what  such  a  plexus  would  become 
if  the  inclosed  basins  were  nearly  filled  up  with  gravel  so  as  to  leave  only 
shallow  hollows.  One  of  these  massives  thus  represents  a  single  broad 
rido'e  of  uneven  surface. 


416  GLACIAL  GRAVELS  OF  MAINE. 

Most  of  the  osar  systems  also  expand  at  various  distances  from  the 
•coast  into  marine  or  g-lacial  lacustrine  deltas. 

When  we  come  within  20  to  40  miles  of  the  coast,  we  find  in  many 
cases  large  plains  of  reticulated  kames.  These  are  much  longer  than  the 
areas  of  reticulated  ridges  found  farther  north.  They  extend  from  230  feet 
up  to  400  or  500  feet.  At  about  the  same  distance  from  the  coast  all  of 
the  osars  begin  to  become  systematically  discontinuous.  Southward  the 
ridges  become  on  the  average  shorter  and  smaller  and  the  intervals  between 
them  longer,  and  in  all  but  a  few  cases  they  apparently  terminate  near  the 
north  ends  of  the  bays  of  the  coast  and  only  a  few  feet  above  sea  level,  as 
lias  been  stated  of  the  discontinuous  osars. 

COMPARISON   OF  CONTINUOUS  WITH   DISCONTINUOUS  OSARS. 

The  osars  are  thus  seen  to  be  somewhat  discontinuous,  but  not  system- 
atically so  until  they  approach  the  coast.  In  almost  all  cases  in  the  interior 
their  interruptions  have  a-  direct  connection  with  the  slopes  of  the  land  or 
places  where  there  would  naturally  be  swift  currents,  as  where  the  rivers 
crossed  hills  or  penetrated  narrow  passes.  But  the  discontinuity  of  the 
coast  is  very  difFerent.  There  the  sediments  are  gathered  more  often  on 
the  hills,  while  the  lowlands  show  no  gravels.  Only  in  comparison  with 
the  coastal  gravels,  then,  are  the  osars  continuous. 

A  plausible  theory  of  osar  formation  postulates  that  it  began  as  a  dis- 
continuous series  of  separated  deposits  left  here  and  there  in  enlargements 
•of  the  channel  or  other  places  favorable  to  sedimentation.  As  the  channel 
was  gradually  enlarged,  sediments  could  be  deposited  more  and  more 
frequently,  until  at  last  continuous  ridges  were  formed.  On  this  hypothesis 
both  the  continuous  and  discontinuous  systems  began  in  the  same  way,  but 
the  osars  went  on  to  a  more  perfect  development. 

Elsewhere  we  stated  numerous  facts  proving  a  gradual  retreat  of  the 
ice  and  forward  advance  of  the  sea  and  bare  land.  The  limited  amount  of 
wave  erosion  proves  that  the  Champlain  elevation  of  the  sea  was  geolog- 
ically brief,  yet  it  afforded  time  for  the  completion  of  a  large  amount  of 
geological  work.  This  fact  rather  favors  the  hypothesis  that  a  continuous 
ridge  begins  as  a  series  of  discontinuous  deposits,  which  gradually  become 
confluent  if  the  flow  of  the  river  is  continued  long  enough,  or  at  least  is  not 
inconsistent  with  it.     Yet  some  weak  points  remain  in  the  argument. 


CONTINUOUS  AND  DISCONTINUOUS  OSARS.  417 

First.  A  ridge  formed  by  filling  in  the  gaps  between  shorter  ridges 
ought  to  show  the  fact  by  its  stratification.  Thus  far  I  have  not  observed 
stratification  of  this  kind.  To  this  it  may  fairly  be  answered  that  the 
number  of  accessible  excavations  in  the  osars  is  too  small  to  be  considered 
crucial  in  the  case. 

Second.  The  assumption  that  the  glacial  streams  continued  to  flow 
longer  in  the  interior  of  the  State  than  near  the  coast  does  not  necessarily 
imply  that  they  were  employed  in  osar  making  for  a  longer  time.  Super- 
ficial streams  could  not  begin  to  build  osars  till  the  melting  reached  the 
debris  in  the  ice.  We  do  not  know  that  subglacial  streams  of  sufficient 
size  to  form  osars  extended  over  all  the  northern  osar  territory  during  all 
the  time -that  elapsed  between  the  forming  of  the  osars  near  the  coast  and 
the  final  melting  of  the  ice  in  the  interior.  This  region  may  have  been 
in  the  zone  of  superficial  streams  during  the  earlier  part  of  this  time,  imtil 
the  subglacial  streams  were  extended  northward. 

Third.  When  we  reach  northern  Maine,  only  short  ridges  have  thus  far 
been  found.  It  is  certain  that  the  ice  lingered  longer  here  than  it  did 
farther  south,  and  it  is  at  least  supposable  that  an  osar  could  be  prolonged 
northward  as  the  ice  receded.  Instead,  the  appearances  are  as  if  the  regions 
of  osar  deposition  were  shifted  from  one  place  to  another  at  the  successive 
stages  of  retreat — that  is,  not  by  a  recession  of  the  same  osar  to  the  extreme 
northern  part  of  the  State,  but  by  a  transfer  of  osar  forming  to  some  other 
glacial  river.  The  hills  of  northern  Maine  would  in  general  not  be  so 
hard  for  osar  rivers  to  surmount  as  many  hills  they  crossed  farther  south. 
But  it  is  impossible  now  to  determine  the  reasons  the  osars  were  not  pro- 
longed to  the  St.  Lawrence-St.  John  watershed  or  beyond  it,  since  we  do 
not  yet  know  all  the  phenomena  of  the  retreat  of  the  ice-sheet.  It  is  a 
generally  accepted  doctrine  that  very  deep  ice  invaded  the  Adirondacks, 
also  the  Green  and  White  mountains,  from  the  north.  This  could  not  have 
happened  unless  the  valley  of  the  St.  Lawrence  River  were  at  one  time 
filled  by  ice  as  far  east  as  the  White  Mountains.  In  a  paper  read  before 
the  Portland  Society  of  Natural  History  in  1881,  I  called  attention  to  the 
apparent  diminishing  of  the  severity  of  glaciation  northward  in  Maine. 
This  was  inferred  from  the  increasing  number  of  areas  where  the  glaciation 
has  not  obliterated  the  preglacial  surface  of  weathering,  also  from  the 
smaller  amoamt  of  attrition  exhibited  by  the  stones  of  the  till.     The  latter 

MON  XXXIV 27 


418  GLACIAL  GRAVELS  OF  MAINE. 

ai-o-ument  would  uot  be  valid  if  what  I  then  assumed  to  be  subglacial  till 
is  really  englacial.  The  scarcity  of  drift  bowlders  in  some  parts  of  eastern 
Aroostook  County  also  points  in  the  same  direction  and  toward  less  intense 
glaciation  eastward  as  well  as  northward.  Recently  Mr.  R.  Chalmers,  of  the 
Geological  Survey  of  Canada,  has  published  the  opinion  that  in  eastern 
Quebec  the  ice  flowed  northward  into  the  Gulf  of  St.  Lawrence.  Obvi- 
ously it  makes  a  great  difference  in  our  views  of  the  ice-sheet  that  covered 
Maine  whether  we  regard  it  as  fed  from  the  Hudson  Bay  region  or  by  a 
n^ve  in  the  upper  St.  John  Valley  that  sent  out  glaciers  north,  east,  and 
south.  The  breadth  of  the  zones  of  accumulation  and  wastage  would  be 
very  differently  estimated  in  the  two  cases.  Such  a  radiate  flow  from  the 
upper  St.  John  Valley  would  naturally  occur  during  the  last  of  the  glacial 
epoch,  no  matter  what  may  have  been  the  history  of  the  time  of  maximum 
glaciation.  Until  the  St.  John-St.  Lawrence  watershed  is  thoroughly 
explored  from  the  White  Mountains  northeastward,  I  do  not  feel  justified  in 
insisting  on  a  local  ndv^  in  northeastern  Maine,  at  least  as  anything  more 
than  an  incident  of  the  decay  of  the  ice-sheet,  although  my  observations 
in  Maine  accord  well  with  that  hypothesis. 

Concerning  the  theory  that  a  continuous  osar  is  iu  all  respects  the  same 
as  one  of  the  systematically  discontinuous  series  in  a  more  advanced  stage, 
it  must  be  admitted  that  it  is  somewhat  probable,  and  yet  there  are  reasons 
for  seriously  doubting  its  tenability.  It  seems  to  be  difficult  to  correlate 
the  two  classes  of  deposits  when  there  were  so  great  differences  m  the 
conditions  under  which  they  were  deposited. 

1.  The  discontinuous  gravels  of  the  coast  were  formed  in  a  region  that 
was  at  one  time  under  the  sea.  At  the  marine  deltas  we  have  direct  proof 
of  subglacial  rivers  flowing  into  the  sea,  and  the  tunnels  appear  to  have 
been  below  sea  level.  Without  assuming  that  the  subglacial  tunnels  were 
beneath  sea  level  at  the  time  either  the  discontinuous  or  the  continuous 
osars  were  deposited,  the  fact  that  the  progressive  changes  of  sea  level  may 
have  caused  the  pressure  of  the  sea  to  extend  farther  and  farther  back 
within  the  tunnels  must  be  allowed  its  full  weight  in  casting  doubt  on  the 
question.  What  would  have  happened  in  the  coast  region  of  Maine  if  the 
sea  had  not  risen  on  the  land!  Before  we  can  admit  that  the  continuous 
ridges  are  only  an  advanced  stage  of  the  discontinuous  series,  and  that  the 


CONTINUOUS  AND  DISCONTINUOUS  OSARS.  419 

difference  is  due  to  causes  arising  wholly  within  the  ice  irrespective  of 
the  sea,  we  must  learn  what  the  development  of  osars  is  beyond  the  reach 
of  submergence,  say  in  Nova  Scotia,  and  show  that  they  conform  to  this 
hypothesis. 

2.  If,  as  seems  probable,  the  deposition  of  sediments  in  the  glacial 
channels  Avas  somewhat  recessive,  the  matter  of  local  slopes  of  the  land 
may  have  been  an  imjDortant  factor  in  determining  the  development  of  the 
gravels.  Near  the  coast  we  are  beyond  the  ranges  of  transverse  hills  with 
little  obstruction  to  the  flow  of  the  ice,  while  northward  the  thinning  ice 
would  be  more  obstructed  by  the  transverse  hills,  except  in  a  few  of  the 
deepest  valleys.  It  may  therefore  have  happened  that  the  continuous  ridges 
of  the  north  were  deposited  when  the  ice  at  the  place  of  deposition  was 
more  nearly  stag-nant  than  when  the  more  southern  gravels  were  deposited. 

3.  It  is  evident  that  the  ice  continued  to  flow  after  the  transverse  hills 
rose  above  the  ice  surface,  for  at  the  low  cols  of  the  hills  there  are  in  numer- 
ous places  small  rounded  swells  of  till,  a  form  of  an  incipient  moraine, 
mai-king  where  small  glaciers  for  a  time  crept  over  the  low  places  in  the 
hill  ranges.  In  general  these  morainal  ridges  are  small,  very  much  smaller 
than  the  Waldoboro  moraine.  At  the  time  the  terminal  overwash  aprons  of 
glacial  sediments  elsewhere  described  were  formed  the  ice  had  retreated  far 
north  of  two  transverse  ranges  of  hills  (counting  from  the  coast  region 
backward)  and  the  ice  front  was  near  the  foot  of  south  slopes.  Here  the 
motion  of  the  ice  would  naturally  be  more  rapid.  The  morainal  ridges 
found  near  Katahdin  Iron  Worlcs  and  East  New  Portland  date  from  this 
period,  and  they  are  rather  larger  than  the  Waldoboro  moraine.  For  some 
years  I  was  not  sure  that  these  ridges  and  mounds  were  not  a  freak  of  the 
subglacial  till,  but  my  observations  in  the  Rocky  Mountains  have  now 
(1893)  convinced  me  that  they  are  moraines  of  englacial  matter. 

We  have  hints  here  and  there,  then,  that  the  rate  of.  ice  advance  varied 
from  time  to  time  during  the  decay  of  the  ice-sheet,  according  as  the  gla- 
cier terminated  on  an  up  or  a  down  slope.  Presumably  the  surface  gradient 
of  the  ice  varied  also.  What  effect  these  changes  would  have  on  the  reces- 
sive development  of  the  glacial  gravels  remains  to  be  determined.  This 
uncertainty  embarrasses  our  comparison  of  the  continuous  ridges  of  the 
interior  of  the  State  with  the  discontinuous  gravels  of  the  coast  region. 


420  GLACIAL  GRAVELS  OF  MAINE. 

WERE  OSARS  DEPOSITED  BY  SUBGLACIAL  OR  BY  SUPERFICIAL  STREAMS? 

Neglecting  basal  melting,  we  divide  the  ice-sheet  into  a  zone  or  area 
of  diffused  superficial  waters,  a  zone  of  superficial  streams,  and  a  zone  of 
subglacial  streams.  But  these  superficial  streams  are  formed  only  where 
there  is  considerable  thickness  of  snow  and  ice,  near  the  margin  of  the  ndvd, 
and  seldom  if  ever  would  englacial  matter  get  up  to  such  a  height  in  the 
ice.  These  streams  may  have  helped  determine  the  courses  of  subglacial 
streams,  but  they  could  not  have  deposited  glacial  gravels  until  the  ice  was 
so  far  melted  that  the  bottoms  of  their  canyons  approached  so  near  to  the 
'ground  that  they  found  englacial  matter  to  roll  and  transport.  The  height 
to  which  basal  morainal  matter  can  rise  in  the  ice,  especially  in  a  hilly 
country,  is  quite  uncertain,  but  most  of  the  englacial  matter  must  have 
been  low  in  the  ice.  Without  assuming  any  definite  height  of  the  englacial 
matter,  we  can  safely  affirm  that  if  any  osars  were  deposited  by  streams 
that  flowed  in  channels  open  above  to  the  air,  it  was  wlien  the  ice  at  the 
place  of  deposition  was  rather  thin.  Such  streams  would  not  be  the  cor- 
relatives of  the  surface  streams  found  far  up  toward  the  ndv^,  but  rather 
of  those  described  by  Russell  near  the  extremity  of  the  Malespina  glacier, 
or  by  Wright  near  the  retreatal  moraines  of  the  Muir  glacier.  It  has  been 
often  assumed  that  those  who  maintain  that  the  osars  were  deposited  by 
superficial  streams  mean  that  they  were  deposited  far  back  from  the 
extremity  of  the  glacier  toward  the  neve,  whereas,  since  most  of  the  osars  are 
stratified,  this  hypothesis  postulates  channels  cut  down  through  the  ice  to  the 
o-round  or  nearly  to  the  ground,  a  condition  that  can  occur  only  near  the 
distal  end  of  the  glacier,  where  the  ice  is  not  very  deep.  Such  supposed 
channels,  open  on  the  top  to  the  air,  might  have  very  different  antecedents. 
They  might  be  formed  by  surface  waters  eroding  and  melting  a  channel 
downward  in  the  ice,  they  might  have  become  open  to  the  air  by  the 
melting  of  the  roofs  of  subglacial  tunnels,  or  a  subglacial  tunnel  might 
have  become  stopped,  either  by  sediment  or  by  ice,  whereby  the  stream 
was  forced  to  rise  and  overflow  on  the  ice  or  form  an  englacial  channel. 
In  case  of  a  subglacial  tunnel  proving  insufficient  to  conduct  all  the  water, 
a  portion  might  often  run  off  on  the  surface,  as  happens  at  the  time  of  the 
discharge  of  the  Marjelen  See,  and  thus  a  single  river  might  have  both  a 
subglacial  and  a  superglacial  outlet.     Such  accidents  might  often  be  facili- 


TESTS  OF  SUBGLACIAL  OH  SUPERFICIAL  DEPOSITION.         421 

tated  by  a  body  of  water  rising  above  the  moutli  of  the  stream  tunnel, 
such  as  the  sea,  or  a  glacial  lake,  or  even  the  dam  found  on  the  proximal 
side  of  hills  over  which  subglacial  streams  flow.  Thus  it  might  often 
happen  that  the  same  osar  river  was  in  different  portions  of  its  course 
subglacial,  englacial,  and  superglacial.  The  important  matter,  from  the 
geological  standpoint,  is  to  be  able  to  recognize  the  deposits  of  these 
diff'erent  kinds  of  streams  in  the  field.  We  therefore  make  a  preliminary 
inquiry  as  to  the  tests  by  which  to  distinguish  them. 

LENGTH   OF    RIDGE. 

I  have  been  able  to  devise  no  crucial  test  between  the  two  kinds  of 
streams  depending  on  the  length  of  the  ridge,  yet  there  is  much  to  prove 
that  the  deposits  in  a  subglacial  tunnel  are  more  likely  to  be  longer  and 
those  in  superficial  channels  shorter.  We  omit  from  this  discussion  the  case 
of  subglacial  streams  becoming  superficial  by  the  disappearance  of  their 
roofs,  since  that  is  a  late  phenomenon  which  happened  at  some  time  to  all 
subglacial  tunnels,  and  is  of  significance  only  when  the  deposit  of  gravel 
continued  after  the  collapse  of  the  roofs. 

Obviously  the  normal  place  for  the  subglacial  river  is  beneath  the  ice, 
and  the  cases  where  it  rises  for  a  time  into  englacial  or  superglacial  chan- 
nels are  exceptions.  Such  portions  of  its  course  must  be  shorter  than  the 
subglacial.  We  may  therefore  eliminate  from  this  comparison  all  except 
two  cases:  The  rising  of  a  subglacial  river  onto  the  surface  near  the  ice 
front,  like  the  kame  river  of  the  Malaspina  glacier,  and  the  case  of  the 
chaimel  supposed  to  be  wholly  due  to  superglacial  waters. 

Regarding  such  terminal  or  marginal  superglacial  channels  as  those  of 
the  Malaspina  glacier,  we  must  admit  that  the  conditions  under  which  they 
occur  are  unusually  favorable  as  compared  with  other  glaciers  or  known 
ice-sheets.  This  glacier  is  situated  near  sea  level;  it  is  so  nearly  stagnant 
that  large  areas  have  become  covered  with  forest;  it  is  in  slow  retreat, 
though  almost  fossil,  and  has  rather  steep  terminal  slopes.  For  some 
reason  the  glacial  streams  have  either  formed  no  subglacial  tunnels  under  a 
marginal  zone  of  uncertain  breadth,  or  the  original  tunnels  have  become 
blocked  by  ice  or  sediment  or  moraines  so  that  the  streams  have  been 
forced  to  form  englacial  tunnels,  which  become  superglacial  by  the  melt- 
ing, away  of  the  overlying  ice,  and  the  streams  continue  such  as  they  flow 


422  GLACIAL  GRAVELS  OF  MAINE. 

down  the  terminal  ice  slope.  If  the  glacier  continues  to  retreat,  it  seems 
probable  that  a  ridge  or  series  of  ridges  such  as  are  now  forming  and  aban- 
doned channels  of  these  rivers  will  be  prolonged  northward  as  far  as  the 
eno-lacial  channels  reach.  This  furnishes  an  observg-tional  basis  for  the  con- 
clusion that  during  the  retreat  of  the  ice-sheet,  wherever  the  ice  was  very 
stagnant  and  the  subglacial  streams  found  their  tunnels  choked  near  their  out- 
lets, they  freely  rose  into  englacial  or  superglacial  channels.  Since  in  doing 
so  they  would  naturally  wander  more  or  less  from  the  course  of  the  original 
tunnel,  a  plexus  of  ridges  would  more  often  be  formed  than  a  single  ridge. 

Now  some  of  the  shorter  osars  of  Maine  belong  to  regions  lying  north 
of  transverse  hills,  where,  after  the  hills  in  front  were  bare,  the  ice  must 
have  been  somewhat  stagnant  and  the  conditions  would  be  favorable  to  the 
formation  of  marginal  ice  canyons  of  this  class.  But  the  longer  osars  go 
up -and  over  hills,  and  some  of  them  occupy  the  longer  north-and-south 
vallej^s,  where  the  ice  flow  would  be  rapid  and  subglacial  streams  would  be 
easily  formed  anywhere  near  the  ice  front. 

One  other  class  of  superficial  channels  in  which  it  is  supposable  that 
osars  were  deposited  is  due  to  waters  of  superficial  melting  cutting  canyons 
in  the  ice  down  to  the  ground.  At  one  time  I  considered  it  a  probable 
hypothesis  that  in  a  country  like  the  interior  of  jMaine,  where  the  ice  over- 
flowed so  many  transverse  hills,  the  subglacial  streams  would  not  readily 
develop,  and  that  here  were  the  proper  conditions  for  surface  streams  to 
continue  to  flow  until  near  the  final  disappearance  of  the  ice.  The  Mala- 
spina  glacier  makes  it  difficult  to  maintain  that  contention.  It  is  not  admis- 
sible that  there  were  in  Maine  any  more  favorable  conditions  for  surface 
streams  than  that  glacier  affords,  except  that  the  summer  melting  may  have 
been  more  rapid  in  the  more  southern  latitude  and  that  there  was  less  water 
warmed  on  bare  land  to  go  down  beneath  the  ice  to  enlarge  the  subglacial 
tunnels.  If  on  so  stagnant  a  glacier  with  so  narrow  crevasses  the  surface 
waters  are  able  to  find  their  way  into  the  subglacial  tunnels,  it  must  be 
admitted  to  be  improbable  that  large  surface  streams  could  exist  anywhere 
near  enough  to  the  margin  of  the  glacier  to  have  reached  the  englacial 
matter  of  the  ice- sheet,  unless  under  extraordinary  conditions  that  could 
have  prevailed  only  for  a  limited  time  and  over  limited  areas.  The  con- 
clusion follows  that  the  great  length  of  the  osars  of  Maine  favors  the 
hypothesis  that  they  were  mainly  formed  in  subglacial  tunnels. 


TESTS  OF  SUBGLACIAL  OR  SUPEEFIOIAL  DEPOSITION.        423 

ANGLE   OF   LATERAL   SLOPE   OF   THE    RIDGES. 

The  lateral  slopes  of  the  ridges  are  in  general  rather  less  steep  in  the 
region  below  than  in  that  above  230  feet.  Not  only  the  lenticular  kames 
biit  also  the  continuous  ridges  have  as  a  rule  rounded  summits  and  gentle 
side  slopes  below  230  feet.  This  is  partly,  but  not  wholly,  due  to  the 
waves  of  the  sea  washing  over  the  tops  of  the  ridges.  Assuming  that  the 
lenticular  eskers  were  formed  beneath  the  ice  and  that  their  gentle  side 
slopes  are  in  part  due  to  the  action  of  the  ice  in  flowing  over  them,  we  can 
not  set  up  that  fact  as  a  crucial  test  for  subglacial  streams.  The  overhang- 
ing walls  of  a  superficial  stream  miay  impinge  on  the  contained  gravels,  and 
when  these  channels  were  greatly  enlarged  at  the  base,  the  contained 
gravels  might  have  as  gentle  slopes  as  the  subglacial.  In  the  interior  of 
the  State  some  of  the  ridges  have  very  steep  lateral  slopes,  and  are  of 
uneven  size,  and  show  hummocky  heaps  like  a  terminal  moraine.  I  do  not 
see  how  we  can  admit  that  the  ice  flowed  over  these  ridges  since  their  com- 
pletion. If  they  are  stratified  at  their  bases,  they  must  liave  been  deposited 
in  superficial  channels,  the  gravel  rising  above  the  basal  enlargements  or 
in  subglacial  tunnels  after  the  ice  had  ceased  to  flow,  or  nearly  so.  The 
test  here  is  not  infallible,  but  the  probabilities  slightly  favor  the  siipei-ficial 
streams. 

INTERNAL   STRUCTURE. 

Sediments  deposited  beneath  the  ice  must  be  stratified  unless  the  strati- 
fication is  obliterated  by  the  pushing  forward  of  the  sediments  by  the  ice. 
Facts  are  elsewhere  recorded  indicating  that  the  ice  had  a  limited  power  to 
disorganize  small  portions  of  eskers  on  their  stoss  sides.  In  various  places 
the  osars  appear  to  have  lost  their  stratification.  At  one  time  I  thought  the 
Corinna-Dixmont  osar  had  been  disorganized  where  it  crossed  valleys,  while 
it  remained  stratified  on  the  hills.  Later  excavations  make  this  doubtful. 
It  is  very  difficult  to  find  excavations  in  Maine  that  do  not  show  more  or 
less  surface  sliding,  unless  they  have  been  made  very  recently.  Seldom 
can  a  sand-and-gravel  bed  be  implicitly  tnisted  after  even  a  single  winter. 
I  therefore  leave  out  of  account  many  cases  of  apparently  pellmell  struc- 
ture observed  in  the  earlier  years  of  my  exploration,  since  my  notes  do 
not  definitely  show  that  the  excavations  had  been  made  during  the  summer 
they  were  examined.     A  residue  remains  where  osars  have  apparently  no 


424  GLACIAL  GRAVELS  OF  MAINE. 

stratification,  yet  plainly  are  composed  of  water-waslied  material.  My 
conclusion  is  that  wliere  the  whole  of  a  ridge  of  till,  from  which  the  finer 
detritus  has  plainly  been  washed  by  water,  has  lost  all  signs  of  stratifica- 
tion and  has  a  pellmell  structure,  the  best  interpretation  is  that  it  was 
deposited  upon  the  ice  in  a  superficial  or  englacial  channel,  and  that  when 
the  ice  underneath  the  sediment  melted,  the  gravel  slid  down  irregularly 
and  the  original  stratification  was  lost. 

A  well-marked  instance  of  an  osar  with  pellmell  structure  is  Indian 
Ridge,  at  Andover,  Massachusetts,  described  many  years  ago  by  Dr.  Edward 
Hitchcock,  and  more  recently  and  fully  by  Prof.  G.  F.  Wright.  Professor 
Dana  has  referred  to  this  ridge  as  a  moraine.  But  the  material  is  slightly 
polished  by  water  and  the  finest  parts  of  the  till  have  been  washed  out  of 
it.  It  is  not  the  ordinary  till  of  the  region,  but  the  residue  after  a  portion 
has  been  removed  by  water.  There  has  also  been  some  water  transporta- 
tion, but  not  much,  or  the  stones  would  be  more  polished.  Moreover,  it 
stands  in  substantially  the  same  relation  to  the  plain  of  stratified  sand  and 
gravel  near  Ballardvale  as  the  osars  of  Maine  stand  to  the  deltas  deposited 
in  glacial  lakes.  In  a  sense  all  glacial  gravels  are  morainal.  It  is  not 
proved  that  Indian  Ridge  was  bodily  transported  horizontally  by  the  ice 
after  its  deposition,  yet  this  may  have  happened.  If  so,  it  will  be  a  dis- 
puted question  whether  to  term  it  a  moraine  or  an  osar.  The  criterion  of 
distinction  between  the  till  and  the  glacial  sediments  proposed  in  this  report 
is  that  the  one  was  brought  to  its  present  position  by  the  ice  and  the  other 
by  water.  In  case  of  ice  transportation  of  Indian  Ridge  as  a  whole,  we 
would  have  a  mingling  of  the  two  processes.  But  where  a  transported 
ridge  maintained  its  individuality  as  a  mass  of  water-washed  matter  distinct 
from  the  adjacent  till,  I  should  not  hesitate  to  apply  the  term  "osar"  to  it. 
It  is  certain  that  few,  if  any,  of  the  osars  of  Maine  were  thus  bodily  trans- 
ported by  the  ice,  at  least  in  the  last  stages  of  their  development.  Where 
an  osar  is  stratified  in  some  parts  of  its  course  and  is  pellmell  in  others, 
there  can  have  been  no  bodily  transportation  on  any  theory  yet  suggested. 
In  general  we  remark:  A  stratified  internal  structure  is  consistent  with 
either  subglacial  or  superglacial  streams.  Pellmell  structure  of  a  large 
mass  of  glacial  gravel  strongly  favors  the  hypothesis  that  it  was  deposited 
on  the  ice,  not  beneath  it.  Quaquaversal  stratification  of  a  cone  (not  due 
to  surface  wash  by  the  sea  waves)  is  in  favor  of  the  theory  that  the  gravel 


TESTS  OF  SUBGLACIAL  OE  SUPERFICIAL  DEPOSITION,        425 

was  deposited  hj  a  siijjerficial  stream  as  it  plunged  into  a  pool  beneath  tlie 
ice,  or  by  a  stream  that  was  wholly  subglacial. 

MEANDEEINGS    OF    A   RIDGE. 

For  convenience,  the  meanderings  may  be  divided  into  two  classes. 

Meanderings  of  the  first  class  are  deflections  for  several  or  many  miles, 
such  as  all  the  longer  osars  and  osar-plains  of  Maine  make  in  order  to  fol- 
low valleys  or  to  find  a  low  pass  throug'h  the  range  of  hills.  Many  of  the 
longer  deflections  along  valleys  are  where  the  ice  was  also  deflected  and 
the  osars  are  parallel  to  the  glacial  flow.  Such  places  would  bq  favorable 
to  the  formation  of  subglacial  tunnels.  Other  long  meanderings  are  found 
in  level  regions  where  the  direction  of  ice  flow  would  be  substantially  the 
same  over  all  the  plain.  If  subglacial  tunnels  were  here  formed,  it  must 
have  been  for  a  part  of  the  distance  transverse  to  the  direction  of  glacial 
flow.  The  Seboois-Kingman-Columbia  osar  leaves  the  valley  of  Seboois 
River,  a  tributary  of  the  Penobscot  River,  and  takes  a  course  for  20  miles 
southeastward  over  two  divides  to  Patten.  It  here  abandoned  a  north- and 
south  valley,  down  which  the  ice  could  freely  flow,  for  a  course  transverse 
to  the  motion  of  the  ice.  Here  the  course  of  the  glacial  river  must  almost 
certainly  have  been  transverse  to  the  direction  of  the  ice  flow,  but  often 
we  are  in  doubt  as  to  the  direction  of  ice  flow  during  the  very  last  of  the 
Glacial  period.  Doubtless  many  of  the  deflections  then  jjrevalent  were 
never  i-ecorded,  since  the  movements  took  place  over  land  already  covered 
by  the  ground  moraine,  and  scratches  made  on  rocks  then  bare  of  till  have 
usually  weathered  away.  Hence  it  may  often  be  that  these  apparent 
deflections  from  the  direction  of  ice  flow  are  not  such  at  all,  as  we  should 
see  could  we  find  the  record  of  the  latest  glaciation. 

I  can  assign  no  physical  cause  for  the  formation  of  subglacial  tunnels 
for  long  distances  in  a  direction  transverse  to  the  flow  of  the  ice,  except  in 
regions  much  broken  by  crevasses,  such,  for  instance,  as  those  near  the 
outer  terminal  moraines.  This  seemed  likely  to  afford  a  crucial  test 
between  the  subglacial  and  the  superglacial  streams,  but  uncertainties  as  to 
the  direction  of  flow  of  the  ice  during  the  very  last  of  the  Ice  period,  and 
as  to  the  power  of  a  superficial  stream  to  cause  an  extension  of  a  subglacial 
tunnel  to  follow  nearly  its  own  course,  have  intervened.  Just  as  we  get  in 
sig-ht  of  a  crucial  test  it  eludes  us. 


426  GLACIAL  GEAVELS  OF  MAINE. 

Of  tlie  longer  meanderings,  all  that  can  be  said  is  that  they  are  trans- 
verse to  any  known  direction  of  flow  of  the  ice. 

Meanderings  of  the  second  class  are  short — from  a  few  rods  to  a  large 
fraction  of  a  mile.  They  are  such  as  might  be  produced  by  either  kind  of 
stream.  They  are  plainly  such  as  would  characterize  the  channel  of  a 
superficial  stream.  On  the  other  hand,  a  subglacial  stream  would  often 
follow  a  transverse  crevasse  for  a  short  distance,  and  thus  could  flow  trans- 
versely to  the  glacier.  It  is  not  certain  how  far  it  could  thus  find  its  way 
transversely.  So,  also,  in  the  northward  extension  of  a  subglacial  tunnel 
its  course  might  often  consist  of  short  zigzags  caused  by  its  attempt  to 
follow  a  superficial  stream  in  a  direction  transverse  to  the  glacier. 

In  general  it  may  fairly  be  urged  that  many  of  the  meanderings  must 
have  been  formed  simultaneously,  and  that  some  of  them  must  have  been 
transverse  to  the  glacier.  Now,  though  ice  is  protean  in  its  resources,  it 
can  not  be  all  things  at  the  same  time.  The  osars  of  Maine  skirt  too  many 
hillsides  and  cross  too  many  valleys  of  natural  drainage  to  permit  the 
admission  that  the  subglacial  waters  could  everywhere  penetrate  the  ice 
transversely  to  the  direction  of  ice  flow.  The  probabilities  are  overwhelm- 
ingly against  the  hypothesis.  For  subglacial  waters  to  flow  transversely  to 
the  motion  of  the  ice  must  have  been  the  exception  rather  than  the  rule  in 
Maine,  except  near  the  ice  front,  where  the  ice  was  much  crevassed.  Near 
the  great  outer  terminal  moraines  and  in  the  tracts  of  reticulated  ridges  or 
kames  the  ice  was  so  crevassed  that  probably  the  subglacial  waters  could 
make  their  way  so  as  to  practically  follow  the  slopes  of  the  land. 

The  longer  meanderings  transverse  to  the  direction  of  ice  flow  certainly 
add  some  difiiculties  to  the  hypothesis  of  subglacial  streams. 

PINNACLES   OR   ELONGATED    CONES. 

On  the  theory  of  subglacial  streams  the  "pinnacles"  or  elongated 
cones  which  here  and  there  rise  above  the  rest  of  an  osar  can  be  accounted 
for  as  having  been  deposited  in  an  enlargement  of  the  subglacial  channel, 
such,  for  instance,  as  forms  at  the  base  of  the  cascade  where  a  superficial 
stream  plunges  down  a  crevasse  into  a  subglacial  tunnel.  On  the  theory 
of  superficial  streams  they  could  be  explained  as  having  been  deposited  in 
the  broad  pool  that  formed  where  a  lateral  tributary  joined  the  main  stream, 
or  in  one  of  the  numerous  pools  that  would  form  at  the  base  of  waterfalls 


TESTS  OF  SUBGLACIAL  OR  SUPERFICIAL  DEPOSITIOISr.        427 

or  rapids.  Another  way  of  accounting  for  them  would  be  by  the  action  of 
ice  dams  such  as  would  naturally  form  when  the  spring  floods  began  to 
break  up  the  ice  and  snow  that  had  gathered  in  the  open  channel  during 
the  preceding  winter.  As  the  Avaters  poured  over  the  dam,  the  unusual 
velocity  would  erode  sediments  that  had  previously  been  deposited  in  the 
channel,  and  they  would  be  piled  up  a  short  distance  below.  On  this 
theory  there  ought  to  be  a  gap  in  the  ridge  just  north  of  the  cone  of  gravel. 
Such  gaps  are  found  north  of  the  "Pinnacle"  at  Pittsfield,  also  north  of 
several  similar  enlargements  of  the  Exeter  Mills-Hermon  osar.  I  have  no 
sections  showing  the  nature  of  the  stratification  at  these  places.  If  the 
stratification  of  the  cones  is  quaquaversal,  it  will  favor  other  theories  rather 
than  the  ice-gorge  theory. 

On  the  whole,  we  must  conclude  that  the  pinnacles  do  not  afiford  a 
satisfactory  test  as  to  whether  the  osars  were  deposited  in  subglacial  or 
superglacial  channels. 

BROAD   AND  MASSIVE   ENLARGEMENTS. 

Such  are  the  so-called  "mountains"  of  Greenbush.  On  the  one 
theory  subglacial  streams  poured  into  a  gradually  enlarging  lake.  On  the 
other  a  very  broad  and  deep  enlargement  was  gradually  made  in  the  super- 
ficial channel.  It  is  only  the  case  of  the  pinnacle  on  a  large  scale.  Biit  in 
this  as  in  many  other  cases  the  rival  theories  may  have  to  compromise. 
A  surface  stream  may  have  poured  into  a  pool,  like  many  of  the  streams  of 
the  Grreenland  ice,  and  have  escaped  as  a  subglacial  stream. 

I  can  discover  here  no  satisfactory  test  for  the  two  theories. 

RETICULATED   EIDGES. 

Reference  is  nere  made  to  the  plexus  of  ridges  into  which  an  osar  often 
expands. 

Superficial  channels  can  become  filled  and  new  ones  formed,  as  every 
river  delta  proves,  and  as  we  see  exemplified  on  every  hillside  during  the 
melting  of  the  snow  and  ice  in  spring.  A  subglacial  channel  can  also 
become  clogged  by  sediment,  and  it  is  easy  to  conceive  circumstances  such 
that  a  new  channel  could  be  more  readily  formed  than  the  old  one  could 
be  enlarged.  The  conditions  under  which  the  reticulated  ridges  were 
formed  will  be  more  fully  discussed  hereafter.     For  the  present  I  only 


428  GLACIAL  GRAVELS  OF  MAINE. 

remark  that  the  plains  of  reticulated  ridges  are  often  found  in  very  level 
regions  not  favorable  to  the  production  of  crevasses,  except  perhaps  those 
of  tension  near  the  ice  margin.  So  far  the  probabilities  favor  the  theory 
of  superficial  streams.  On  the  whole,  the  reticulated  ridges  can  not  be 
admitted  as  affording  a  crucial  test. 

PROBABLE   VELOCITIES   OF   THE   TWO    KINDS   OF   STREAM. 

In  maii}^  places  in  the  osars  we  find  rounded  bowlderets  and  bowlders 
in  the  midst  of  much  finer  material.  To  account  for  these  bowlders  we 
may  postulate  moderate  currents  for  most  of  the  time,  with  now  and  then 
a  sudden  flood;  or,  more  often,  such  bowlders  probably  fell  from  the  ice 
onto  the  gravel  in  the  bed  of  a  glacial  stream  and  were  rounded,  not  so 
much  by  being  themselves  rolled  forward  as  by  the  attrition  of  smaller 
stones  pushed  past  them.  Such  bowlders  are  very  common  in  the  reticu- 
lated ridges  of  western  Maine.  In  these  cases  we  need  not  postulate  more 
rapid  currents  than  would  be  necessary  to  move  the  finer  matter.  If  we 
make  proper  allowance  for  such  adventitious  bowlders,  obviously  the  size 
of  the  transported  rocks  and  stones  will  measure  the  velocities  of  the 
cuiTcnts. 

If  most  or  all  of  the  morainal  debris  was  contained  in  the  lowest  part 
of  the  ice,  as  is  generally  believed,  then  the  superficial  streams  that  are 
found  near  the  neve  line,  or  anywhere  high  upon  the  ice,  would  be  glacial 
torrents,  but  not  osar-forming  de'bris.  Obviously,  only  those  portions  of 
superglacial  channels  that  are  in  ice  containing  debris  can  be  of  significance 
in  osar  formation.  The  theor}^  that  such  streams  could  form  osars  where 
the  ice  was  deep  must  stand  or  fall  with  the  theory  that  the  debris  reached 
high  elevations  within  the  ice. 

We  need  not,  then,  in  estimating  the  velocities  of  the  superficial 
streams,  consider  the  general  surface  gradient  of  the  ice,  but  only  that  of 
the  marginal  portion  rising  to  the  height  of  the  englacial  matter,  perhaps  a 
few  hundred  feet  above  the  ground.  Here  for  a  few  miles,  say  2  to  5 
miles,  we  can  grant  to  the  superficial  streams  waterfalls,  rapids,  pools,  and 
all  other  accidents  of  open  surface  channels,  and  velocities  both  greater  and 
less  than  those  due  to  the  surface  gradient  of  the  ice. 

On  the  other  hand,  the  velocities  of  subglacial  streams  are  only  in 
part  determined  by  the   slopes  of  the  land.     When  the  capacity  of  the 


TESTS  OP  SUBGLAGIAL  OR  STJPEEFIOIAL  DEPOSITIOif,        429 

tunnel  suffices  to  cany  off  the  water  without  its  vising  in  the  crevasses,  the 
velocity  is  chiefly  determined  by  the  land  slopes,  but  any  surplus  causes 
some  of  the  water  to  rise  in  the  crevasses  as  into  the  standpipes  of  an 
aqueduct  system.  The  only  limit  to  the  effective  "head"  in  the  crevasses  is 
determined  by  the  height  of  the  tops  of  the  crevasses  over  which  the  water 
can  overflow  on  the  surface.  During  the  summer  floods,  when  the  supply 
of  water  is  large  as  compared  with  the  capacity  of  the  tunnels,  the  water 
may  often  be  driven  by  the  pressure  of  hundreds  of  feet  of  water  in  the 
tunnel  and  crevasses.  In  other  words,  the  effective  "head"  of  subglacial 
streams  can  not  exceed  the  vertical  differences  in  height  between  the  mouth 
of  the  tunnel  and  the  top  of  the  nearest  crevasse  connecting  with  the  tunnel, 
and  therefore  subject  to  overflow.  When  we  come  to  compare  the  two  kinds 
of  stream  with  respect  to  velocity,  we  find  a  mechanism  in  both  cases  for 
producing  high  velocities  with  corresponding  coarseness  of  sediments.  It 
is  doubtful  whether  we  are  able  to  distinguish  between  the  two  kinds  of 
stream  by  the  size  of  separate  fragments  of  the  sediments. 

EROSION   OF   THE   GROUND   MORAINE. 

Both  kinds  of  stream  would  erode  the  subglacial  till  while  in  contact 
with  it.  A  subglacial  stream  being  necessarily  in  contact  with  the  lower  till 
the  whole  time  of  its  flow,  ought  to  erode  it  more  than  a  superficial  stream, 
which  could  reach  it  only  after  it  had  cut  its  way  to  the  bottom  of  the  ice. 

Erosion  beneath  the  osars. — Tliis  Is  a  dlfficult  subjcct  of  invcstigation,  owing  to 
the  character  of  the  exposures.  Artificial  excavations  do  not  go  deejD 
enough,  and  at  the  rivers  which  have  eroded  the  osars  there  is  almost 
always  surface  sliding  of  the  gravel  from  above.  At  Pittsfield  Village  the 
Sebasticook  River  has  eroded  one  side  of  the  Hartland-Montville  osar  and 
the  gravel  distinctly  lies  upon  the  bare  rock.  At  numerous  places  the 
gravel  near  the  edge  of  the  osar  overlies  the  till,  but  this  may  be  due  in 
part  to  surface  sliding  since  deposition.  At  Clinton  and  various  other  places 
excavations  show  that  the  gravel  near  the  axis  of  the  ridge  extends  nearly 
to  the  rock,  and  then  the  base  of  the  gravel  was  not  reached.  The  facts 
observed  are  too  few  for  generalization,  but  point  to  considerable  erosion  of 
the  ground  moraine  beneath  the  osars. 

Erosion  of  the  ground  moraine  in  places  not  now  covered  by  gravel. Aloilg     the     COUrSeS     of 

the  osar  rivers  are  many  gaps  in  the  ridges  where  we  can  now  see  the 


430  GLACIAL  GEAVELS  OF  MAINE. 

former  beds  of  these  rivers.  In  a  few  places,  as  northwest  of  North  Mon- 
mouth and  northeast  of  Hogback  Mountain  in  Montville,  a  ravine  of  erosion 
has  been  excavated  in  the  tilL  Generally  where  the  larger  glacial  rivers 
crossed  the  hills,  or  on  steep  down  slopes,  we  do  not  find  a  definite  raAdne 
of  erosion,  but  the  till  is  scanty  or  almost  wholly  absent  over  an  area  several 
times  as  broad  as  the  ordinary  breadth  of  the  osar.  In  these  places  there  is 
less  till  than  in  the  surrounding  country,  and  we  must  admit  a  large  removal 
of  till,  both  the  englacial  and  the  subglacial.  On  the  other  hand,  there 
has  been  but  little  erosion  of  tiU  in  several  passes  and  on  several  di-vades 
where  the  circumstances  would  appear  to  be  favorable  to  erosion.  Among 
these  may  be  named  the  pass  south  of  Grrand  Lake  on  the  Houlton  system, 
the  divide  near  Forest  station  on  the  Hersey-Danforth  branch,  the  Katahdin 
system  in  a  low  pass  situated  just  northwest  of  the  Whalesback  in  Aurora, 
The  Notch  in  Garland,  and  the  valley  of  the  east  branch  of  Georges  River 
in  Montville. 

We  have,  then,  several  cases  of  very  great  erosion  of  the  till  on  the 
line  of  the  osar  rivers,  man}-  cases  where  there  has  been  a  moderate  erosion, 
and  perhaps  an  equal  number  of  cases  where  there  are  now  no  gravels  yet 
there  has  been  but  little  erosion  of  the  till  by  large  osar  rivers.  No  posi- 
tive inferences  can  as  yet  be  drawn  from  the  observed  facts  bearing  on  the 
question  of  subglacial  versus  superglacial  streams,  though  the  probabilities 
rather  favor  the  supei-ficial  streams.  On  the  theory  of  subglacial  streams 
it  is  difficult  to  account  for  such  facts  as  are  elsewhere  recorded  as  being 
observed  at  The  Notch  in  Garland.  While  there  are  a  large  number  of 
cases  where  the  subglacial  hypothesis  is  equally  in  accord  with  the  facts, 
and  in  some  cases  better  in  accord  with  them  than  the  hypothesis  of  super- 
ficial streams,  there  are  other  places  where  superficial  streams  are  as 
strongly  indicated  by  the  facts.  All  this  points  to  the  conclusion  that  the 
osar  rivers  were  in  some  places  subglacial  and  in  other  places  superficial  or 
englacial.  This  may  be  bad  for  the  symmetry  of  theories,  but  seems  to  be 
true  to  nature. 

GAPS   IN   THE   OSARS. 

Both  subglacial  and  superglacial  streams  could  sweep  their  channels 
free  from  sediment  at  places  where  the  channel  was  narrower  or  shallower, 
or  where  the  slopes  of  the  land  gave  unusual  velocity  to  the  current.  The 
velocity  of  subglacial  streams  is  certainly  often  much  greater  than  that  due 


TESTS  OF  SUBGLAOIAL  OR  SUPERFICIAL  DEPOSITION.        431 

to  the  slopes  of  the  land.     It  is  doubtful  if  continuity  or  noncontinuity . 
furnishes  a  crucial  test  between  the  two  kinds  of  streams,  but  the  pheno- 
inena  near  the  coast  make  it  probable  that  noncontinuity  is  a  distinguishing 
feature  of  an  early  stag'e  of  subglacial  sedimentation. 

SIZE    OF    THE    OSARS. 

If,  as  I  assume,  the  only  superficial  streams  (if  there  were  any)  that 
were  concerned  directly  in  osar  formation  were  situated  near  the  ice 
front,  then  the  probability  of  such  a  stream  forming-  a  large  ridge  is  not 
so  great  as  that  a  long  subglacial  stream  would  form  one.  The  only 
•way  such  a  stream  could  make  a  very  large  ridge  is  retreatally,  and 
even  then  it  is  difficult  to  account  for  one,  especially  for  the  stratified  osars. 
For  sedimentation  in  the  present  stratified  condition  could  not  have 
begun  till  the  ice  in  the  bottom  of  the  superficial  channel  was  melted, 
and  since  that  would  happen  only  late,  it  seems  improbable  that  a  very 
large  ridge  could  collect  after  that  time  before  the  ice  was  all  melted. 
The  great  size  of  such  ridges  as  the  Whalesback,  Aurora,  favors  the 
subglacial  hypothesis. 

LOCAL  VERSUS  PAR- TRAVELED  MATERIAL. 

Professor  Chamberlin  has  shown  that  in  the  West  the  osars  are  com- 
posed of  local  matter  clearly  differentiated  from  the  englacial  till,  which 
was  derived  from  the  distant  crystalline  hills.  His  argument  is  that  sub- 
glacial streams  would  reach  the  local  matter,  whereas  superficial  streams 
would  rarely  do  this,  but  their  sediments  would  consist  of  englacial  matter 
from  a  distance. 

Several  disputed  questions  are  involved  in  the  application  of  this  argu- 
ment to  Maine,  such  as  the  manner  in  which  basal  ddbris  got  up  into  the 
ice,  the  angle  of  its  supposed  ascent,  the  height  it  attained,  etc.  In  many 
places  in  Maine  I  have  not  been  able  to  draw  so  fine  distinctions  as  those 
of  Professor  Chamberlin  between  subglacial  till  of  local  and  englacial  till  of 
distant  origin.  There  are  multitudes  of  places,  especially  in  eastern  Maine, 
where  local  matter  appears  in  the  upper  part  of  the  till  within  a  few  feet  or 
rods  from  the  northern  edge  of  an  outcrop  of  rock.  This  is  especially 
noticeable  in  the  case  of  granite  bowlders.  Whether  this  is  subglacial  or 
englacial  till  is  a  question  for  determination.     I  have  not  always  been  able 


432  GLACIAL  GEAVELS  OF  MAINE. 

to  disting'uish  them.  The  apphcation  of  this  test  is  not  so  simple  as  it  is 
in  the  West.  Only  in  eastern  Maine  are  the  outcrops  such  that  the  test 
can  be  applied  without  considerable  study  of  the  local  rocks.  In  Enfield 
and  Prospect,  granite  bowlderets  and  some  bowlders  appear  in  osars 
within  much  less  than  a  mile  from  the  north  edge  of  a  granite  area — 
in  fact,  it  may  be  only  a  few  rods.  On  the  other  hand,  in  Aurora  and 
eastward  toward  Deblois  the  water  transportation  has  been  so  great  that 
almost  all  the  gravel  has  traveled  several  to  many  miles.  This  was  in  the 
course  of  the  Katahdin  osar  river,  one  of  the  largest  glacial  rivers  of  the 
State.  The  law  seems  to  be  that  the  local  matter  appears  in  osars  of  mod- 
erate or  small  size. 

But  these  ridges  at  Enfield  and  Prospect  are  stratified;  hence,  on  the 
superglacial  hypothesis,  the  bottom  of  the  superficial  canyon  had  probably 
reached  the  ground  at  the  time  of  deposition;  and  if  so,  would  contain 
basal  and  local  matter.  The  most  noticeable  thing  about  these  granite 
bowlderets  and  bowlders  is  that  they  appear  on  the  tops  of  ridges  30  to  50 
feet  in  height.  I  do  not  see  how  superficial  streams  can  elevate  bowlderets 
and  bowlders,  whereas  the  subglacial  streams  of  the  Malespina  glacier  do 
raise  such  coarse  matter.  If  the  osars  were  deposited  by  superficial  streams, 
the  bowlderets  and  bowlders  in  question  must  have  been  raised  by  ice 
movements,  and  when  released  from  the  grasp  of  the  ice  by  the  melting, 
they  tumbled  into  the  canyon.  If  so,  they  must  have  risen  in  the  ice  30 
to  50  feet  within  a  fraction  of  a  mile,  and  that,  too,  on  level  ground  or  on 
a  gentle  northern  slope,  as  in  Enfield,  not  from  the  brows  of  crags  or  hills. 
This  is  only  one  of  numerous  instances  where  the  superglacial  hypothesis 
demands  that  the  englacial  debris  should  arise  very  rapidly  in  the  ice  and 
to  considerable  height. 

After  making  allowance  for  local  difficulties,  it  appears  to  me  that  on 
the  whole  the  sudden  appearance  of  local  matter  in  the  smaller  osars  and 
to  such  a  height  in  the  ridges  distinctly  favors  the  hypothesis  that  the  osars 
were  formed  by  subglacial  streams.  At  one  time  it  seemed  to  me  incredible 
that  the  subglacial  streams  could  raise  bowlderets,  and  especially  bowlders, 
against  the  force  of  gravity.  Anyone  who  has  doubts  on  this  subject  can 
have  them  all  removed  by  inspection  of  the  device  for  placer  mining  termed 
the  hydi-aulic  elevator. 


TESTS  OF  SUBGLACIAL  OE  SUPERFICIAL  DEPOSITION.         433 

PHENOMENA    OF    GLACIAL    KIVERS    IN    CROSSING    HILLS    AND    VALLEYS. 

As  before  noted,  the  hills  of  Maine  are  in  large  part  transverse  to  the 
direction  of  glaciation.  Hence  the  courses  of  the  longer  glacial  rivers  very 
often  led  them  up  and  over  hills.  On  the  steeper  down  slopes  the  behavior 
of  subglacial  and  superglacial  streams  would,  perhaps,  not  be  very  unlike, 
but  in  the  valleys  and  on  the  northern  slopes  of  hills  their  action  might 
be  quite  different.  The  osars  are  in  the  main  stratified,  and  the  only 
superglacial  streams  here  referred  to  are  those  the  bottoms  of  whose  can- 
yons had  reached  the  ground  at  the  time  of  deposition  of  the  gravel,  or  so 
nearly  that  the  stratification  was  only  obliterated  locally,  if  at  all,  during 
the  unequal  melting  of  the  subjacent  ice.  This  I  conceive  could  take  place 
only  in  the  marginal  region  near  the  ice  front.  Some  distance  back  from 
the  front  a  superglacial  channel  might  contain  sediment,  if  the  englacial 
debris  reached  so  high  as  the  ice,  but  it  would  overlie  such  deep  ice  that 
if  left  in  this  condition  the  unequal  melting  of  the  subjacent  ice  would 
usually  confuse  the  stratification.  It  is  not  assumed,  except  for  the  sake 
of  argument,  that  such  streams  helped  to  deposit  the  osars. 

We  first  suppose  a  subglacial  tunnel  to  cross  a  transverse  valley  and 
hill,  as  in  the  accompanying  diagram,  fig.  32.  The  water  in  the  tunnel 
below  the  horizontal  line 
AB  touching  the  top  of 
the  hill  Avill  form  a  dam 
or  lakelet  and  be  in  equi- 
librium, like  the  water  j-ig.  32.— Icleal  section  or  glacIal  stream  channels  orossiufj  trausversB  valleys. 
nf    n     tSPWrpr    trar>  ^VltPV  JJBC,  glacier;  J.B2>,  subglacial  stream;  _B,  C,  ti-ansrerse  hills. 

will  rise  to  the  same  level  in  all  crevasses  opening  into  the  tunnel.  As  fast 
as  water  flows  from  the  north  into  the  trap  an  equal  amount  will  flow 
southward  over  the  hill  at  B.  The  general  law  of  velocities  in  the  tunnels 
is  that  if  the  tunnels  increase  in  capacity  from  north  to  south  at  an  equal 
ratio  with  the  increasing  supply  of  drainage  waters,  other  things  being- 
equal,  the  velocities  will  be  uniform  throughout  the  whole  courses  of  the 
tunnels.  But  there  are  at  least  two  causes  for  the  tunnel  being  smaller  in 
the  valley  than  elsewhere — that  is,  relatively  to  the  supply  of  glacial  waters. 
First.  The  depth  of  ice,  and  presumably  the  rate  of  inward  flow  of  the 
tunnel  walls,  is  greater  in  the  valley  at  D. 

MON  XXXIV 28 


434  GLACIAL  GRAVELS  OF  MAINE. 

But  then  the  inward  How  of  the  walls  is  antag-onized  by  the  outward 
pressure  of  the  contained  water.  Also  in  Maine  no  glacial  rivers  are 
known  to  have  ilowed  over  hills  higher  than  200  to  250  feet,  except  in  one 
extreme  case  of  400  feet,  measured  above  the  valleys  lying  to  the  north  of 
them.  This  represents  only  one-fifteenth  to  one-twentieth  of  the  maximum 
depth  of  ice.  If  we  assume  so  great  plasticity  of  the  ice  that  so  small  a. 
difference  in  thickness  could  make  much  difference  in  the  sizes  of  the  sub- 
glacial  tunnels  in  the  two  situations,  it  seems  difficult  to  account  for  very 
deep  crevasses  or  subglacial  channels.  On  the  whole,  it  seems  improbable 
that  so  small  differences  in  thickness  of  ice  would  much  restrict  the  enlarge- 
ment of  the  subglacial  tunnels  in  the  valleys ;   yet  it  might  to  some  extent. 

Second.  It  will  be  seen  that  the  basal  ice  north  of  the  hill  is  perma- 
nently bathed  in  cold  waters,  and  that  the  crevasses  also  are  filled  to  the 
same  height  as  the  top  of  the  hill.  All  the  waters  of  local  melting  that 
pour  into  the  crevasses  in  this  part  of  the  tunnel  must  more  or  less  become 
mixed  with  the  cold  waters  of  the  crevasses,  and  their  heat  will  largely  be 
expended  in  melting  the  walls  of  the  crevasses,  not  in  expanding  the  tun- 
nels, just  as  has  been  jjointed  out  in  the  case  of  a  glacier  flowing  down  into 
the  sea.  Now  some  of  these  dams  or  permanent  bodies  of  subglacial  water 
must  have  been  several,  perhaps  many,  miles  in  length.  Thus  the  subglacial 
dam  north  of  Springfield,  in  the  course  of  the  Seboois-Kingman-Columbia 
osar  river,  was  at  least  15  miles  long,  and  that  of  the  Portland  system  north 
of  North  Woodstock  extended  as  far  as  Andover,  a  distance  of  20  miles. 
Because  of  the  greater  subsidence  toward  the  north,  the  length  would  at 
that  time  be  somewhat  greater  than  now.  Tlie  ice  would  be  many  years 
in  passing  over  such  distances,  and  the  cumulative  effects  of  such  dissipa- 
tion of  the  energy  that  otherwise  would  help  to  enlarge  the  tunnels  must 
have  been  considerable  wherever  the  courses  of  the  glacial  rivers  were  so 
nearly  parallel  to  the  ice  flow  that  the  same  body  of  basal  ice  in  its  progress 
was  thus  continuously  modified  for  a  term  of  years. 

We  aie  therefore  justified  in  assuming  that  in  the  longer  valleys  situated 
north  of  hills  crossed  by  the  glacial  rivers  the  subglacial  tunnels  would 
be  small  relatively  to  the  supply  of  water,  and  the  velocities  would  be 
rather  high  during  all  the  earlier  stages  of  ice-channel  sedimentation.  Ridges 
deposited  at  this  time  Avould  be  rather  narrow  and  composed  of  coarse 
material.     Indeed,  the  sedimentation  might  often  be  of  the  discontinuous 


TESTS  OF  SUBGLACIAL  OR  SUPERFICIAL  DEPOSITION.        435 

type,  the  streams  iu  places  having-  velocity  sufficient  to  clear  their  channels 
of  sediments. 

Later,  when  the  ice  became  thin  and  could  no  longer  flow  u^d  the  hill, 
this  stagnant  condition  would  favor  the  enlai-gement  of  the  tunnels  in  spite 
of  the  interference  of  the  basal  waters.  When  the  ice  surface  sank  to  the 
top  of  the  transverse  hill,  or  near  to  it,  the  stream  could  no  longer  escape 
southward  over  the  hill.  It  would  then  escape  transversel)^  to  the  east  or 
west  along  the  top  of  the  ice  or  between  the  ice  front  and  the  hill,  or  by 
transverse  subglacial  channels.  But  in  most  cases  the  rivers  crossed  the 
hills  by  passes  leading  up  to  low  cols,  and  the  hills  at  the  sides  of  these 
valleys  would  hold  in  the  stream  till  the  ice  had  melted  back  to  the  north 
ends  of  the  passes.  The  retreat  of  the  ice  from  the  tops  of  the  divides  back 
to  the  northern  ends  of  the  passes  might  occupy  several  or  even  man}^  years, 
and  during  all  this  time  there  would  be  a  marginal  body  of  water  between 
the  ice  and  the  top  of  the  col,  absorbing  heat  direct  from  the  sunlight.  This 
water  would  most  rapidly  extend  itself  northward  along  the  line  of  the  sub- 
glacial  river,  partly  tln-ough  mechanical  erosion  and  the  heat  of  the  stream 
waters  and  partly  because  the  ice  near  the  tunnel  would  already  have  become 
somewhat  honeycombed  by  melting  within  the  crevasses  above  the  tunnel. 
Thus  the  frontal  lake  would  be  narrowly  V-shaped,  extending  deeply  into 
the  ice,  as  an  enlargement  of  the  original  tunnel,  expanding  toward  the 
south  till  it  passed  beyond  the  ice  front  and  extended  across  the  whole 
valley  or  pass.  Into  this  deltoid  body  of  water  the  glacial  river  poured  its 
sediments.  The  coarser  matter  was  left  near  the  mouth  of  the  sul^glacial 
tuimel,  and  thence  the  sediments  would  grow  finer  obliquely  outward.  If 
the  lake  became  veiy  broad  as  compared  with  the  size  of  the  river,  we  might 
even  have  a  delta  deposited  in  it  like  that  in  Unity  and  Thorndike,  or  in 
Dover,  northwest  of  The  Notch,  Grarland.  If  so  narrow  that  the  velocity 
of  the  current  was  less  checked,  an  osar  terrace  or  broad  osar  would  be 
"deposited  in  the  marginal  lake,  like  the  terraces  that  border  the  Whalesback 
in  Woodstock,  Milton,  and  Rumford.  In  the  lake  or  within  narrower  ice  chan- 
nels near  its  northern  end,  a  plexus  of  reticulated  ridges  might  be  deposited. 
The  development  of  these  broad-channel  or  lacustrine  sediments  would  go 
on  retreatally  northward  till  the  ice  front  receded  to  the  north  ends  of  the 
passes,  when  the  waters  might  or  might  not  be  diverted  into  new  courses 
back  of  the  ice  front,  but  in  any  case  the  sfirface  of  the  marginal  lake  began 


436  GLACIAL  GRAVELS  OF  MAINE. 

to  sink  to  lower  level.  The  suddenness  with  which  the  development  of  the 
gravels  was  often  arrested  and  the  absence  of  transition  beds  laid  down  in 
transverse  channels  or  of  terraces  between  the  end  of  the  ice  and  the  hills 
that  rose  in  front  of  it,  may  perhaps  be  Ijest  interpreted  as  proving  that  the 
ice  sometimes  became  so  greatly  shattered  near  the  front  that  the  waters 
spread  outward  and  often  transversely  in  a  multitude  of  small  delta  branches, 
none  of  which  were  large  enough  to  deposit  gravels  in  the  short  time  that 
elapsed  before  the  ice  was  all  melted  in  that  region.  The  nature  of  the 
development  of  the  glacial  sediments  during  the  retreat  of  the  ice  down  the 
northern  slope  and  thence  back  to  C  (fig.  32,  p.  433)  would  depend  on  many 
conditions,  and  we  might  expect  many  different  manifestations.  One  of  the 
critical  points,  so  to  speak,  is  at  the  northern  end  of  the  permanent  water 
trap  at  C.  At  the  time  of  diminished  flow  in  the  fall  and  Avinter  the  stream 
would  no  longer  fill  its  tunnel  and  more  or  less  sediment  would  drop  where 
it  entered  the  permanent  water  trap  ABB.  Now  and  then  this  might  result 
in  the  channel  being  clogged  during  the  floods  of  the  succeeding  summer, 
forcing  the  waters  to  rise,  and  causing  the  formation  of  an  englacial  or  super- 
ficial channel  and  the  opening  of  a  lake  at  the  place  where  the  stream  rose 
on  the  surface  or  flowed  down  again  after  passing  the  obstruction  in  the  tun- 
nel. In  such  a  lake  broad  ridges  or  an  osar-plain  might  form,  or  reticulated 
ridges,  but  not  a  delta,  unless  it  was  very  large  compared  to  the  river.  Or 
the  broad  channel  or  lake  might  be  extended  continuously  across  the  valley, 
perhaps  by  the  confluence  of  a  number  of  lakes  that  originally  formed  in 
the  course  of  the  channel.  When  the  watei's  forced  a  transverse  passage 
north  of  the  hill  early  enough  to  permit  considerable  enlargement  and  depo- 
sition of  gravels,  we  have  the  phenomenon  of  delta  or  diverging  and  trans- 
verse branches  like  the  intricate  reticulations  of  tlie  gravel  systems  of 
southwestern  Maine.  Here  the  rocks  are  mostly  granitic  and  the  till  is  very 
abundant.  This  must  have  favored  the  clogging  of  the  subglacial  tunnels 
and  the  digression  of  the  streams  to  new  channels  that  often  diverged  widely 
from  the  original  channels. 

We  next  consider  what  is  conceived  to  be  the  probable  behavior  of  a 
superglacial  stream  in  the  same  situation,  i.  e.,  during  the  retreat  of  the  ice 
over  a  valley  situated  north  of  a  hill  crossed  by  an  osar  system,  premising 
that  it  must  be  able  to  deposit  stratified  osars,  and  hence  that  the  bottom 
of  its  canyon  must  reach  the  ground  or  nearly  to  it.     At  first  the  bed  of  the 


TE^TS  OF  SUBGLACIAL  OR  SIJPBKFIGIAL  DEPOSITION.         437 

stream  lies  approximately  parallel  to  the  ice  surface  EB.  As  the  ice  melts, 
the  bed  will  come  to  occupy  the  position  of  the  dotted  line  and  dip  beneath 
the  horizontal  hne  AB.  A  marginal  lake  will  form  in  front  of  the  ice,  just 
as  in  the  supposed  case  of  a  subglacial  stream.  The  melting  will  be  most 
rapid  along  the  bed  of  the  stream  and  near  the  mouth  where  it  enters  the 
lake,  and  thus  the  form  of  the  lake  will  probably  not  differ  much  from  that 
when  a  subglacial  stream  flows  into  it.  In  this  broad  channel  or  lake  we 
might  have  reticulated  ridges  or  an  osar-plain  deposited.  As  the  ice 
retreated  toward  the  bottom  of  the  valley  it  would  seem  that  the  glacial 
o-ravel  ought  to  be  more  abundant  in  that  region  than  anywhere  on  the 
northern  slope.  It  certainly  would  be  so,  and  of  frontal  or  overwash  char- 
acter, unless  the  superficial  stream  forms  a  glacial  lake  at  some  point 
toward  the  north,  which  arrested  the  transportation  of  sediments  from  the 
north.  We  can  admit  transverse  escape  over  the  ice  to  the  east  or  west  or 
arou.nd  the  front  of  the  ice  next  the  hills,  but  not  subglacial  or  englacial 
escape,  since  this  would  be  inconsistent  with  the  supposed  conditions,  i.  e.. 


Fig.  33.— Sectiou  of  valley  between  Sherman  and  Springfielil.    Jf,  at  ilacwahoo:  K,  at  Kingman ;  P,  at  Prentiss. 

ice  so  stagnant  that  the  crevasses  were  not  sufficient  to  enable  a  subglacial 
tunnel  to  be  formed.  This  is  a  large  demand  to  make  so  near  the  ice  front, 
but  my  purpose  is  to  give  the  theory  every  possible  chance  to  account  for 
the  field  phenomena. 

These  general  principles  have  been  discussed  with  a  view  to  their 
application  to  certain  localities. 

The  great  Seboois-Kingman-Columbia  osar  system  descends  the  valley 
of  Molunkus  Stream  from  Sherman  to  Kingman,  where  it  crosses  the  Mat- 
tawamkeag  River  nearly  at  right  angles,  and  then  ascends  the  other  side  of 
the  Mattawamkeag  basin,  through  Webster,  Prentiss,  and  Springfield,  where 
it  crosses  a  divide  near  200  feet  higher  than  the  river  at  Kingman.  This 
great  osar  river  has  left  gravels  for  40  miles  or  more  north  of  Kingman, 
where  it  crossed  the  deep  transverse  valley  of  the  Mattawamkeag.  Fig.  33 
represents  the  system  in  this  part  of  its  course.  The  slope  of  the  Molunkus 
Stream  is  moderately  steep  from  Sherman  to  Macwahoc ;  then  the  valley 


438  GLACIAL  GRAVELS  OF  MAI]SfE. 

is  nearly  horizontal  to  Kingman,  and  thence  the  slope  rises  moderately 
steeply  again  to  Springfield.  From  Sherman  to  Macwahoc,  and  again 
from  Prentiss  southward,  the  gravel  takes  the  form  of  a  broad  osar,  or  osar 
terrace,  of  sand  and  rather  fine  gravel.  At  Macwahoc  and  Prentiss  it 
expands  into  complexes  of  reticulated  ridges  inclosing  kettleholes  and  com- 
posed of  coarse  gravel,  cobbles,  and  bowlderets.  For  3  or  4  miles  near 
Kingman  the  system  takes  the  form  of  a  narrow  osar  of  rather  fine  sand, 
and  is  somewhat  interrupted.  It  is  the  narrowness  and  fineness  of  this 
ridge  near  the  bottom  of  the  transverse  valley  that  specially  demands 
explanation.  The  noncontinuity  is  in  part,  and  possibly  may  be  wholly, 
due  to  postglacial  erosion.  On  both  theories  there  were  broad  osar  chan- 
nels north  of  Macwahoc  and  south  of  Prentiss.  Both  postulate  a  lake- 
like expansion  at  Macwahoc,  and  another  at  Prentiss,  in  which  or  near  its 
margin  was  left  a  plexus  of  reticulated  ridges.  On  the  subglacial  theory 
the  tunnel  would  be  relatively  small  where  it  crossed  the  transverse  valley, 
and  sedimentation  scanty  or  in  narrow  ridges.  This  corresponds  well  with 
the  osar  at  Kingman,  but  for  a  long  time  I  had  ditficulty  in  accounting 
for  the  fineness  of  the  sediment.  Now  Macwahoc  and  Prentiss  are  not  far 
from  the  same  elevation,  and  only  3  miles  or  so  from  opposite  ends  of  the 
subglacial  dam.  During  the  retreat  a  broad  channel  was  formed  north  of 
the  divide  in  Springfield,  which  extended  itself  as  far  north  as  the  complex 
in  Prentiss.  North  of  there  the  sediments  were  scanty  or  absent  until  the 
lake  or  broad  channel  was  opened  at  Macwahoc.  If  the  opening  of  this 
lake  was  due  to  a  clogged  chaimel,  the  water  may  have  overflowed  later- 
ally, so  that  the  old  channel  was  never  thereafter  used,  except  for  local 
drainage,  and  thus  only  sand  would  be  deposited.  But  as  the  channel  was 
not  permanently  clogged,  the  coarse  sediment  from  the  north  would  mostly 
stop  in  the  lake  at  Macwahoc  and  only  the  finer  pass  on  across  the  valley 
to  gradually  fill  the  old  tunnel  or  parts  of  it  just  preceding  the  time  that  the 
ice  retreated  so  far  north  that  the  tunnel  was  disused.  On  the  superglacial 
theory  the  order  of  events  must  have  been  substantially  the  same.  The 
opening  of  the  lake  at  Macwahoc  and  deposition  of  the  plexus  of  reticu- 
lated ridges  is  essential  to  both  theories.  But  the  distance  between  the 
complexes  of  Macwahoc  and  Prentiss  is  about  10  miles,  and  we  must  sup- 
pose deposition  in  one  began  immediately  after  the  other  was  ended,  or 
there  would  be  an  osar-plain  or  other  body  of  retreatal  gravels  left  over  the 


TESTS  OF  SUBGLACIAL  OE  SUPERFICIAL  DEPOSITION.        439 

lower  parts  of  the  Mattawamkeag  Valley  near  Kingman.  This  enlarges 
our  claims  for  superglacial  osar  rivers  from  small  streams  near  the  ice  front 
to  the  long  osar  rivers  themselves. 

Thus  we  here  discover  no  crucial  test  between  the  two  rival  theories, 
though  the  difficulties  of  the  superglacial  hypothesis  are  increased  with 
every  complication,  such  as  that  involved  in  the  claim  of  their  ability  to 
form  glacial  lakes  in  which  stratified  gravels  were  deposited,  and  hence  must 
have  reached  to  the  bottom  of  the  ice,  or  nearly,  and  that,  too,  at  a  distance 
of  10  miles  back  from  the  ice  front.  It  is  a  matter  of  observation  that  pools 
which  presumably  would  expand  into  lakes  in  a  time  of  stagnation  of  the 
ice  movement  are  formed  in  Grreenland  where  large  surface  streams  flow 
beneath  the  surface  and  escape  subglacially,  but  no  instances  are  recorded 
where  they  form  very  deep  lakes  and  escape  supei-ficially. 

In  all  cases  known  to  me  where  the  osars  went  up  and  over  rather  hig-h 
hills  with  long  valleys  to  the  north,  such  as  the  Portland  system  north  of 
North  Woodstock,  the  Smyrna  series  north  of  Danforth,  the  Bridgton  series 
north  of  Baldwin,  the  north  end  of  the  Peru-Buckfield  system,  and  others, 
the  field  phenomena  prove  that  the  gravels  of  earliest  deposition  north  of 
the  higher  hills  were  deposited  in  rather  narrow  tunnels  and  that  the  streams 
had  considerable  velocity.  There  are  several  cases  of  reticulated  ridges  on 
the  northern  (up)  slopes,  which  may,  perhaps,  be  accounted  for  on  either 
theory.  Where  broad  osars  or  lake  deltas  are  found  in  such  situations  they 
are  plainly  a  rather  late  if  not  a  retreatal  phenomenon. 

A  sufficient  cause,  as  it  appears  to  me,  has  been  pointed  out  for  the 
restriction  of  the  subglacial  tunnels  north  of  these  hills,  but  I  know  of  none 
on  the  superglacial  hypothesis.  At  Kingman  we  may  ^Derhaps  account  for- 
the  absence  of  broad-channel  phenomena  by  the  convenience  of  the  broad 
channel  or  lake  at  Macwahoc,  but  in  other  places  there  is  no  such  way  of 
accounting-  for  the  lack  of  broad-channel  deposits  in  the  valleys  north 
of  hills. 

On  the  whole,  I  conclude  that  the  subglacial  hypothesis  is  strengthened 
and  the  superglacial  weakened  by  the  behavior  of  the  glacial  rivers  where 
they  crossed  transverse  valleys  and  hills. 

It  is  not  here  meant  to  assert  that  all  the  broad  osar  channels  date  from 
so  late  a  period  of  the  ice-sheet  as  that  assumed  in  this  discussion. 

It  must  be  admitted  that  the  various  tests  for  distiuOTiishing-  in  the 


440  GLACIAL  GRAVELS  OF  MAIiSTE. 

field  between  osars  deposited  respectively  by  subglacial  and  superficial 
streams  are  not  so  definite  as  is  desirable.  Probably  all  the  field  phenomena 
can  be  accounted  for  on  either  hypothesis,  though  sometimes  only  by 
cumbrous  complications  that  in  the  end  must  break  down  any  hypothesis 
that  has  to  resort  to  them.  Often  in  the  last  fifteen  years  I  have  discov- 
ered what  was  hoped  to  be  an  unmistakable  and  crucial  test,  only  to  find 
my  quest  unsuccessful. 

Some  of  the  elements  of  the  problem  of  the  osars  have  been  set  forth 
above.  It  remains  to  correlate  them  with  others  in  order  to  get  a  more 
0-eneral  view  of  the  osars,  their  history  and  causation.  This  is  reserved 
for  a  subsequent  chapter. 

BROAD  OSARS   OR  OSAR  TERRACES. 

Several  of  the  osars,  after  preserving  the  form  of  a  two-sided  ridge 
with  arched  cross  section  for  a  distance  of  5  to  30  miles  from  their  north 
ends,  expand  into  a  level-topped  plain  varying  in  breadth  from  one-sixteenth 
to  three-fourths  of  a  mile.  These  plains  or  terraces  contain  no  kettleholes 
proper,  though  the  surface  is  sometimes  gently  undulating.  More  often  it 
is  very  level.  The  material  of  the  plain  is  ustially  rather  fine  gravel  and 
sand.  In  some  cases  they  are  found  as  terraces  on  hillsides  far  above  any 
ordinary  stream,  and  can  without  difficulty  be  at  once  pronounced  as  of 
glacial  origin.  But  they  often  extend  across  the  whole  of  the  valleys  in 
which  they  are  situated,  and  so  closely  resemble  valley  drift  that  they  can 
with  difficulty  be  distinguished  from  that  form  of  alluvium.  The  principal 
tests  for  distinguishing  the  two  kinds  of  sediments  are  the  following: 

1.  Topographically,  the  broad  osars  occupy  the  same  position  with 
respect  to  the  osars  lying  north  of  them  as  they  would  if  they  were  depos- 
ited by  the  same  glacial  rivers.  The  existence  of  the  osar  north  of  them 
indicates  that  a  glacial  river  flowed  from  the  north  to  the  point  where  the 
osar  expands  into  the  broader  plain.  This  river  must  be  accounted  for.  It 
could  not  disappear  except  in  a  lake  or  the  sea,  or  by  flowing  out  of  the  ice 
into  a  valley  where  the  ice  had  alread}^  melted.  But  the  osar  terrace  is  not 
a  delta  proper,  showing  a  complete  transition  from  the  gravel  to  sand  and 
finally  clay.  It  was  not  deposited  in  a  lake  proper  or  in  the  sea;  at  least  the 
velocity  of  the  water  was  only  partially  checked.     The  glacial  river  must 


BEOAD  OSAES  OE  OSAE  TEEEAOES.  441 

therefore  have  continued  in  a  channel  confined  wholly  or  in  part  by  ice,  or 
it  flowed  into  a  valley  over  which  the  ice  had  melted  all  the  way  to  the  sea. 
In  the  last-named  case  the  sedimentary  plain  is  a  frontal  delta,  and  ought  to 
extend  continuously  down  the  valley  to  the  level  of  the  sea  as  it  existed  at 
the  time  of  deposition.  If  at  any  point  the  sedimentary  plain  in  question 
leaves  the  valley  in  which  it  was  deposited  and  takes  a  course  on  the  hill- 
sides or  passes  over  hills  into  another  drainage  basin,  we  have  proof  of  the 
continuity  of  the  glacial  river  sediments  over  even  the  lower  parts  of  the  val- 
ley where  for  a  time  they  were  found  in  form  so  much  resembling  valley  drift. 
The  sediments  here  termed  "  osar  terraces"  cross  hills  and  valleys  just  the 
same  as  the  osars,  and  these  topographical  relations  are  inconsistent  with  the 
hypothesis  that  they  are  valley  drift,  though  in  the  valleys  their  situation 
is  such  that  they  must  since  deposition  have  been  subject  to  the  action  of 
streams  and  often  have  been  eroded  by  them,  and  often  were  overlain  with 
valley  drift.  If  an  osar-plain  were  confined  wholly  to  a  single  valley  we 
should  have  no  topographical  test  to  distinguish  it  from  valley  drift.  This 
does  not  apply  to  the  osar-plains  of  Maine. 

2.  The  material  of  the  beds  of  ordinary  streams  in  every  part  of  the 
State  I  have  ^dsited  has  been  carefully  examined  with  a  view  to  determining 
the  amount  of  attrition  to  which  the  existing  stream  gravel  has  been  sub- 
jected. Everywhere  the  testimony  of  the  gravel  of  the  osar-plains,  when 
compared  with  that  of  the  adjacent  streams  having  the  same  slopes  and  size 
of  drainage  basin,  is  substantially  the  same.  The  average  shape  of  the 
gravel  of  the  osar-plains  shows  immensely  more  waterwear  than  the  gravel 
of  the  existing  streams.  The  proofs  of  this  are  abundant  and  overwhelm- 
ing. Only  in  the  mountain  regions  where  the  slopes  are  100  or  more  feet 
per  mile  do  the  stones  in  the  beds  of  streams  show  rounded  forms  at  all 
comparable  to  those  of  the  glacial  gravels. 

3.  The  quantity  of  the  broad  osar  sand  and  gravel  is  usually  much 
greater  than  the  valley  drift  of  the  adjoining  regions. 

4.  Many  of  the  osar  terraces  do  not  extend  across  the  whole  of  the  val- 
leys in  which  they  are  situated,  and  show  no  tendency  to  expand  into  a  delta 
at  a  broad  part  of  their  valleys,  but  sometimes  end  at  one  or  both  sides  in 
a  well-defined  bluff  rising  quite  abruptly  above  the  level  of  the  adjacent 
land.  At  such  places  we  must  grant  they  were  bordered  by  ice  walls,  or 
the  alluvium  would  have  spread  obliquely  outward  across  the  valley. 


442  GLACIAL  GRAVELS  OF  MAINE. 

While  the  sediments  of  broad  osars  are  prevailingly  finer  than  that 
of  narrow  osars,  yet  these  plains  show  decided  variations  in  coarseness 
of  material  in  different  parts  of  their  courses,  just  as  the  osars  do.  Thus 
the  great  Portland  system  on  a  north  slope  in  Rumford  and  Milton  consists 
of  fine  gravel  and  a  large  amount  of  sand.  Approaching  the  top  of  the 
divide  at  North  Woodstock,  we  find  gravel  and  cobbles,  while  on  the  south 

slope  from  North  Wood- 
stock past  Bryants  Pond 
to  North  Paris   it  consists 

Fig.  34. — Diagrammatic  section  across  osar-plain;  Woodstock  and  Milton. 

ot   pebbles,  cobbles,  bowl- 
derets,  and  many  bowlders  2  to  4  feet  in  diameter,  all  very  much  waterworn. 

In  many  places  the  osar-plains  have  been  much  eroded  by  small 
streams  and  boiling  springs.  Invariably  the  erosion  has  been  most  rapid 
toward  the  sides  of  the  plain,  leaving  a  central  uneroded  ridge  resembling 
an  osar  in  external  form.  In  some  cases  the  central  ridge  is  composed  of 
much  coarser  material  than  the  ground  on  each  flank,  but  I  have  not  been 
able  to  find  sections  satisfactorily  showing  the  nature  of  the  stratification  of 
the  central  and  lower  parts  of  the  ridges.  At  the  tops  of  the  ridges  and  in 
the  plain  at  their  sides  the  strata  are  nearly  horizontal,  or  somewhat  cross- 
bedded,  dipping  a  little  toward  the  south. 

Fig.  34  shows  a  section  across  the  osar-plain  in  Rumford  and  Milton. 
The  central  ridge  is  here  known  as  the  "Whalesback,"  and  has  aboiit  the 
same  height  as  the  uneroded  terraces  at 
the  sides  of  the  valley. 

Fig.   35    shows  a    section    across    the      fig.  35.-Diagrammaticsectiouacro.sso3ai-plain:valIey 
~w~,  1       •         r-i  1  of  Bog  Brook,  Canton. 

valley   oi    Bog    Jt5rook  in   banton  and 

Livermore.     The  broad  osar  has  here  been  eroded  by  two  brooks,  one  on 

each  side  of  the  central  ridge,  and  they  flow  in  opposite  directions.     The 

central  ridge  here  rises  several  feet  higher  and  the  material  is  much  coarser 

than  tlie  terraces  of  sand  and  gravel  that  are  found  on  each  side  of  the 

valley. 

There  must  l)e  a  reason  why  the  central  ridge  invariably  resists  erosion 
better  than  the  matter  at  its  sides.  In  most  cases  the  ridge  is  plainly  com- 
posed of  much  coarser  matter.  I  have  found  no  sections  showing  that  an 
ordinary  narrow  osar  with  arched  cross  section  lies  along  the  axis  of  the 
osar-plain,  though  this  is  probably  the  case  where  the  central  ridge  rises 


f    '^    *.'% 


.m  ffy^(l      ^ 


^ 


0      '' 


^* 


7    ^f 


k/^%      ,LMK 


BEOAD  OSAES  OE  OSAE  TEEEACES.  443 

above  the  terraces.  But  the  broad  .osar  can  easily  be  differentiated  into 
the  following  tracts:  (1)  An  axial  belt  of  coarse  composition  and  with  the 
material  very  much  waterworn.  (2)  Bordering  terraces,  oOmetimes  not  so 
high  as  the  central  ridge,  composed  of  finer  materials  and  often  not  so  much 
waterworn. 

These  facts  point  to  the  following  interpretation:  that  first  there  was 
an  ordinary  narrow  osar  channel  in  which  more  or  less  coarse  gravel 
accumulated,  and  that  as  the  channel  subsequently  broadened  the  original 
osar  was  more  or  less  washed  away  and  incorporated  with  the  growing 
marginal  terraces.  These  conclusions  are  strengthened  by  the  fact  that  in 
several  cases  an  osar  expands  for  several  miles  into  a  broad  osar  and  sub- 
sequently narrows  again  into  the  ordinary  osar  type  of  ridge.  The  broad 
osar  or  osar  terrace  is  thus  seen  to  differ  in  no  essential  character  from  the 
narrow  osar  except  that  it  has  advanced  a  stage  farther  in  its  development. 
The  history  of  this  development  was  in  part  as  follows: 

First  there  was  an  ordinary  narrow  osar  river.  Whether  this  had 
begun  to  deposit  gravels  within  its  channel  previous  to  the  great  enlarge- 
ment of  the  channel  is  to  be  determined  in  each  case  separately,  for  these 
rivers  appear  to  have  had  different  histories.  We  need  not  here  inquire 
whether  the  narrow  rivers  flowed  in  subglacial  vaults  or  in  superficial  can- 
yons open  to  the  air.  The  flow  of  water  increased,  and  so  gradually  that 
the  ice  at  the  sides  of  the  original  channel  could  be  melted  and  eroded 
at  a  corresponding  rate.  I  defer  the  question  whether  the  enlargement 
took  place  retreatally.  While  the  channels  remained  comparatively  narrow 
only  coarse  matter  could  be  dropped  in  them,  and  as  the  channel  widened 
the  central  osar  was  more  or  less  washed  away  and  spread  laterally  into  the 
sides  of  the  broadening  channel.  The  broader  the  channel  the  finer  the 
sediments  that  were  deposited  in  it,  unless  there  was  a  corresponding  increase 
in  the  supply  of  Avater.  It  is  due  to  a  gradual  broadening,  accompanied  by 
rapid  currents,  that  the  central  osar  is  not  abruptly  differentiated  from  the 
bordering  terraces  of  finer  sediments. 

Were  the  broad  osar  channels  roofed  with  ice?  Two  facts  can  be 
named  as  especially  bearing  on  this  question. 

1.  The  rai-ity  of  till  on  or  within  the  broad  osars. 

In  the  northern  part  of  Baldwin  are  a  number  of  bowlders  very  little 
if  in  any  degree  polished  by  water,  yet  situated  upon  and  within  the  sand 


444  GLACIAL  GRAVELS  OF  MAINE. 

and  fine  gravel  of  a  broad  osar.  They  are  exceptional,  and  the  question  of 
their  origin  is  discussed  elsewhere. 

In  general  we  find  in  the  broad  osar  terraces  no  unpolished  stones  or 
bowlders  that  can  be  regarded  as  till  dropped  from  the  roof  of  an  ice  arch, 
though  near  the  borders  of  these  plains  the  stones  have  received  much  less 
attrition  from  water  rolling  than  have  the  stones  of  the  osars  or  central 
parts  of  the  broad  osars. 

2.  The  great  breadth  of  the  terraces. 

If  the  broad  osar  channels  wei-e  roofed  with  ice,  the  size  of  the  ter- 
races demands  ice  arches  of  great  lengths  of  span,  numbers  of  them  up  to 
one-fourth  of  a  mile,  several  one-half  of  a  mile,  and  a  few  three-fourths  of 
a  mile.  These  would  be  very  long  spans  for  bridges  of  high-grade  iron 
and  steel.  If  the  arches  sagged  and  were  supported  on  the  gravels  or  on 
abutments  of  ice,  we  ought  to  find  the  terrace  uneven  on  its  surface,  with 
kettleholes  and  reticulated  ridges.  The  sizes  of  the  subglacial  channels 
would  be  so  restricted,  too,  that  onlj-  coarse  sediment  would  be  deposited 
all  the  way  out  from  the  central  ridge  to  the  margins.  We  now  and  then 
find  reticulations  and  hummocky  ridges  in  the  midst  of  osar  terraces  that 
may  have  had  such  a  history,  but  the  broad  osars  proper  are  very  level  in 
cross  section  and  contain  such  fine  sediments  that  they  must  have  been 
deposited  in  large  channels  where  the  flow  of  the  water  was  moderate. 

The  interpretation  of  these  facts  is  further  discussed  below. 

FORMATION  OF  THE  BROAD   OSAR  CHANNELS. 

Among  the  methods  whereby  the  ordinary  osar  channel  might  become 
broadened,  we  may  mention  the  following,  premising  that  these  channels 
had  somewhat  parallel  sides: 

1.  Subglacial  channels  were  enlarged  laterally  and  subglacially  to  the 
full  breadth  of  the  channel. 

This  theory  would  require  us  to  assume  that  the  larger  bowlders,  at 
least  over  most  of  the  State,  were  contained  in  the  basal  ice.  For  the  broad 
osar  is  composed,  as  a  rule,  of  rather  fine  material,  and  does  not  carry 
bowlders  such  as  ought  to  have  fallen  from  the  roofs  of  so  broad  tunnels  if 
the  englacial  bowlders  were  high  in  the  ice. 

The  difficulties  of  this  hypothesis  are  very  great  if  not  insuperable. 


FOEMATION  OF  BROAD  OSAR  CHANNELS.         445 

The  breadth  of  these  broad  channels  (one-eighth  of  a  mile  to  one-half  mile 
or  more)  is  such  that  it  seems  inadmissible  to  postulate  ice  arches  of  such 
dimensions  without  their  roofs  collapsing.  Russell  reports  the  roof  of  a 
stream  of  the  Lucia  glacier  collapsing.  This  stream  is  about  150  feet  wide.-^ 
Now,  although  the  subsidence  of  the  roof  in  this  case  appears  on  the  ice 
surface  only  so  long  as  the  roof  is  not  very  thick,  it  by  no  means  follows  that 
there  is  not  also  an  inward  flow  of  the  roof  and  walls  with  increasing  depth. 
But  the  roofs  of  the  broad  osar  channels  would  be  from  ten  to  twenty  times 
as  broad  as  this  stream  of  the  Lucia  glacier.  To  postulate  self-supporting- 
roofs  is  an  enormous  demand.  I  do  not  see  even  one  feature  of  the  gravels 
or  any  propertv  of  ice  that  warrants  the  assumption.  Locally  we  can  con- 
ceive of  such  arches  floating  on  the  slack  water  north  of  hills  crossed  by 
the  osar  rivers,  but  the  broad  osars  are  also  found  on  southern  slopes  where 
there  could  be  no  slack  water. 

Perhaps  the  principal  question  involved  in  the  problem  is  this:  Where 
are  we  to  find  the  supply  of  heat  necessary  to  melt  and  enlarge  such  great 
channels "?  For  I  assume  that  melting  is  a  greater  cause  of  enlargement 
than  erosion.  The  channels  in  which  were  deposited  the  broad  osars,  the 
osar  bowlder  clay,  the  narrow  marine  deltas,  also  the  lake-like  enlarge- 
ments in  which  were  deposited  the  peculiar  formation  elsewhere  named 
"  lacustrine  massives,"  are  all  a  connected  series  of  phenomena.  Any  com- 
plete theory  must  account  not  onlj^  for  these  very  broad  channels  but  also 
for  the  narrow  ones.  If  we  assume  that  the  broad  osar  channels  were 
formed  subglacially,  we  may  as  well  assume  that  lacustrine  massives  5  to 
10  miles  long  and  1  to  2  miles  wide  were  also  formed  subglacially.  But  if 
we  assume  that  these  very  broad  channels  were  subglacial,  how  are  we  to 
account  for  the  narrowness  of  the  osars  proper!  Ordinary  subglacial 
streams  depend  for  the  heat  with  which  they  enlarge  their  tunnels  chiefly 
on  waters  of  superficial  melting,  slightly  warmed  before  the  plunge  down 
the  crevasses.  This  supply  of  heat  is  small  and  only  moderately  enlai'ges 
the  tunnels.     This  accounts  for  the  narrowness  of  the  earlier  tuunels.     We 

'Nat.  Geog.  Mag.,  vol.  3,  p.  107,  May,  1891.  "The  course  of  the  stream  below  the  mouth  of 
the  tunnel  may  be  traced  for  some  distance  by  scarps  in  the  ice  above,  formed  by  the  settling  of  the 
roof.  Some  of  these  may  be  traced  in  the  illustrations.  When  the  roof  of  the  tunnel  collapses  so 
completely  as  to  obstruct  the  passage,  a  lake  is  formed  above  the  tunnel,  and  when  the  obstruction 
is  removed  the  streams  draining  the  glacier  are  flooded." 

This  description  refers  ro  the  tunnel  by  which  the  stream  descends  beneath  the  ice  after  having 
risen  to  the  surface  and  flowed  a  mile  aud  a  half  on  the  ice. 


446  GLACIAL  GKAVBLS  OF  MAI^"E. 

can  assume  that  during  the  decay  of  the  ice-sheet  this  enlargement  went 
on  at  a  somewhat  uniform  rate,  so  that  at  last  they  attained  the  dimensions 
of  the  broad  osar  channels.  But  if  so,  how  can  we,  on  the  subglacial 
hypothesis,  account  for  the  discontinuous  gravels,  where  the  channels  con- 
necting the  successive  lake-like  enlargements  were  so  narrow  and  the 
resulting  velocity  was  so  great  that  for  long  distances  no  sediment  was 
deposited  f  Besides,  wear  of  surface  streams  ought  to  enlarge  the  channels 
somewhat  uniformly — that  is,  produce  ordinary  osar  channels ;  but  I  see 
no  method  of  wear  by  which  these  extraordinary  local  enlargements  would 
be  pi-oduced. 

On  the  other  hand,  if  we  postulate  a  body  of  water  open  to  the  sun- 
hght,  we  at  once  find  a  sufficient  local  supply  of  energy  to  produce  these 
local  enlargements,  in  the  heat  absorbed  directly  from  the  sun  by  the  water 
of  the  channel,  pool,  or  lake.  AVe  are  also  saved  from  a  self-destructive 
assumption  of  so  great  power  of  the  ordinary'  superficial  waters  of  the 
glacier — such  as  are  exposed  for  only  a  short  time  to  the  sun  and  then 
plunge  beneath  the  ice — in  enlarging  their  channels,  as  would  make  it 
impossible  to  account  for  the  narrow  tunnels. 

On  the  subglacial  hypothesis  the  broad  osar  channels  originated  as 
ordinary  narrow  osar  rivers,  the  roofs  of  whose  tunnels  subsequently  dis- 
appeared. Were  these,  then,  superficial  streams!  In  my  earlier  writings 
they  were  so  interpreted,  and  formed  one  of  the  principal  arguments  for 
the  belief  that  superficial  streams  were  able  to  cut  canyons  down  to  the 
bottom  of  the  ice  and  deposit  stratified  sediments  within  them  resting  on 
the  till  or  rock.  Professor  Chamberlin  suggests  that  they  were  neither" 
subglacial  nor  superficial.  It  is  probable  the  water  that  flowed  in  them  was 
in  other  portions  of  the  glacier  a  part  of  the  subglacial  drainage.  They  are 
in  general  equally  consistent  with  either  the  subglacial  or  the  superglacial 
hypothesis,  and  therefore  must  certainly  be  withdrawn  as  evidence  of 
superglacial  streams.  On  tlie  subglacial  hypothesis  all  tunnels  at  some 
time  lost  their  roofs,  but  these  are  supposed  to  have  lost  theirs  before  osar 
deposition  was  completed. 

2.  Another  hypothesis  would  be  about  as  follows: 

As  the  subglacial  tunnels  attained  considerable  breadth,  and  the  ice 
became  thin,  sagging  or  collapse  of  the  roofs  became  more  rapid  and  the 
cross  section  of  the  tunnel  became  a  more  and  more  flattened  arch.     In 


FOEMATION  OF  BEOAD  OSAE  CHANNELS.         447 

process  of  time  the  middle  of  the  arch  might  rest  on  the  previously  depos- 
ited osar,  where  there  was  one,  but  in  any  case  there  would  often  be  more 
enlargement  of  the  tunnel  laterally  than  in  height.  Where  the  course  of 
the  glacial  river  was  approximately  parallel  to  the  ice  flow,  the  slow  set- 
tling of  the  roof  of  the  tunnel  would  continue  to  modify  the  same  mass 
of  ice  in  its  progress  for  a  term  of  years  and  cause  a  somewhat  continuous 
depression  of  the  surface.  In  this  depression  or  valley  surface  waters 
would  collect  and  melt  moi'e  or  less  ice  before  reaching  a  crevasse.  Many 
conditions,  such  as  the  extension  of  the  ndvd  line  northward,  might  cause 
an  increased  supply  of  waters  with  flooding  of  the  subglacial  tunnels. 
Collapse  of  the  roof  or  clogging  of  the  channel  would  cause  the  Avater 
to  rise  into  englacial  or  superficial  channels,  and  the  latter  would  follow 
the  depression  caused  by  the  settling  of  the  roof  and  often  cause  the  forma- 
tion of  temporary  surface  lakes.  AYhere  the  Avaters  rose  in  crevasses  or 
went  down  again  into  them  after  passing  an  obstruction,  deep  pools  Avould 
form  if  the  overfloAv  was  long  continued  or  often  repeated.  When  one  or 
more  pools  were  formed  or  openings  were  made  through  the  roofs,  the 
heat  of  the  sun  would  be  absorbed  in  increasing  amount  by  the  subglacial 
waters,  the  separate  pools  Avould  gradually  become  confluent  in  a  contin- 
uous channel  open  above  to  the  sun,  and  this  chaimel  would  then  rapidly 
broaden  till  it  sometimes  came  to  extend  across  a  whole  A^alley.  Many  of 
the  conditions  for  oversupply  of  water  as  compared  with  tunnel  capacity 
would  depend  on  purely  glacial  conditions,  such  as  rate  of  melting,  rate 
of  ice  flow,  etc.  When  the  falling  of  a  single  block  of  ice  into  a  tunnel 
may  have  changed  the  course  of  a  glacial  riA^er  overflowing  on  the  ice 
into  a  new  valley  in  the  ice  surface,,  it  will  not  be  expected  that  Ave  shall 
be  able  to  trace  all  the  accidents  of  broad-channel  formation.  North  of 
hills  crossed  by  the  osar  rivers  this  process  was  probably  often,  perhaps 
always,  assisted  by  the  pool  of  slack  water  there  collected,  and  here  the 
enlargement  may  have  often  proceeded  as  the  extension  of  a  fringing  or 
marginal  lake  formed  north  of  the  hill. 

This  hypothesis,  postulating  the  change  in  the  development  of  an 
osar  system  from  a  narrow  to  a  broad  osar  and  again  to  the  narrow 
type,  demands  that  we  shall  not  regard  the  broadening  of  the  channel  as 
extending  recessively  northward.  Rather  it  took  place  locally,  leaving 
reaches  of  narrow  osar  in  the  course  of  the  same  system.     We  can  admit  a 


448  GLACIAL  GRAVELS  OF  MAINE. 

cousiflerable  enlargement  as  taking  place  at  the  base  of  the  crevasse  where  a 
superficial  stream  pours  beneath  the  ice ;  but  I  do  not  see  how  we  can  admit 
local  supplies  of  ordinary  superficial  waters  in  such  quantities  as  would 
account  for  the  disappearance  of  the  roofs.  The  overflow  theory  postulates 
known  processes,  and  seems  to  be  sufficient  for  the  work  accomplished. 
Local  stoppages  of  the  tunnels  here  and  there  would  cause  the  local  disap- 
pearance of  the  roofs,  with  the  consequent  broadening  of  the  channels. 

When  we  come  to  apply  the  hypothesis  to  the  enlargement  of  the 
narrow  marine  delta  channels  and  those  of  the  border-clay  channels  that 
were  beneath  the  sea,  we  find  special  difficulties.  The  ebb  and  flow  of  the 
tide  and  the  temperature  of  the  sea  would  introduce  new  elements  into  the 
analysis,  but  theii*  quantitative  significance  is  uncertain. 

Applying  these  principles  to  both  the  up  and  the  down  slopes  of  the 
land  as  we  go  south  along  the  courses  of  the  osar  rivers,  I  have  failed  to 
find  any  constant  relation  between  the  land  slopes  and  the  enlargements  of 
broad  osar  channels,  at  least  such  as  would  warrant  the  prediction  of  their 
occurrence  at  particular  places  or  slopes.  If  there  is  such  a  rule  it  is  that 
in  most  cases  a  broad  osar  extends  for  some  distance  north  of  the  tops  of 
hills  crossed  by  the  osars.  On  the  steeper  down  slopes  there  may  have 
been  the  same  broad  channels,  but  quite  often  no  gravel  was  left  for  1  to  3 
miles  south  of  the  hilltops,  and  we  have  only  inferential  evidence  of  the 
breadth  of  the  channel.  Also  the  alternation  of  broad-chamiel  deposits 
having  a  horizontal  surface  in  cross  section  with  the  area  of  reticulated 
ridges  will  require  more  detailed  study  before  correlation  of  these  deposits 
with  topographical  features  can  be  asserted.  Indeed,  they  may  often  have 
had  no  connection  with  the  land  surface  and  have  depended  on  ice  condi- 
tions alone. 

RETICirLATED  ESKEKS  OR  KAMES. 

In  external  appearance  these  uneven  and  hummocky  complexes,  wliich 
show  an  endless  variety  of  ridge  and  hollow,  are  perhaps  the  most  remark- 
able of  all  the  deposits  left  by  the  glacial  rivers.  They  afford  all  grada- 
tions of  complexity  from  the  simple  branching  of  a  ridge  into  two  ridges 
which  soon  come  together  again,  up  to  the  great  plexus  3  or  4  miles  broad, 
its  surface  covered  with  a  jumble  of  heaps,  mouiids,  cones,  and  ridges, 
inclosing  all  forms  of  hollows,  funnels,  hopperholes,  kettleholes,  basins,  and 


RETICULATED  ESKEES  OR  KAMES.  449 

"Roman  theaters,"  many  of  which  are  so  deep  as  to  inclose  lakelets  without 
visible  outlets. 

Probably  the  phenomena  of  all  the  glaciated  countries  will  have  to  be 
compared  before  we  are  able  to  explain  these  interesting  formations  in  all 
their  details. 

The  most  important  facts  concerning  the  reticulated  ridges  are  the  fol- 
lowing : 

1.  Their  geographical  distribution.  The  most  remarkable,  of  these 
plains  are  situated  in  southwestern  Maine,  where  they  are  connected  with 
the  Conway-Ossipee  kame  plains  of  New  Hampshire.  Almost  all  the  osars 
and  other  gravel  systems  here  and  there  expand  into  a  plexus  of  reticulated 
ridges,  but  they  are  not  large  except  in  the  granitic  areas.  The  granite 
outcrops  of  eastern  Maine  are  much  smaller  than  those  of  western  Maine, 
and  the  general  slope  of  the  land  is  not  so  steep.  For  these  and  perhaps 
other  reasons  the  reticulated  eskers  of  that  part  of  the  State  do  not  cover 
so  broad  areas. 

2.  Their  relations  to  long  gravel  systems.  The  reticulated  kames  are 
not  a  distinct  class  of  systems,  but  a  peculiar  form  into  which  the  longer 
gravel  systems  here  and  there  expand.  They  were  deposited  by  the  same 
glacial  rivers  that  left  the  osars  and  other  types  of  gravels. 

3.  Their  relations  to  relief  forms  of  the  land.  All  the  longer  gravel 
systems  at  some  part  of  their  course  pass  from  one  basin  of  natural  di-ain- 
age  to  another,  and  most  of  them  do  so  repeatedly.  In  the  interior  of 
the  State  the  areas  of  reticulated  ridges  into  which  the  osars  and  broad 
osars  expand  are  rather  small.  They  are  situated  variously  with  respect  to 
the  slopes  of  the  land,  being  found  on  both  up  and  down  slopes  and  in 
level  regions.  Thus  going  up  and  over  the  hills  and  across  the  valleys,  the 
great  river  at  last  penetrated  all  the  higher  transverse  ranges  of  hills  along 
the  low  passes  and  came  out  into  a  region  of  broad  valleys  which  soon 
merge  into  the  sea-border  plain,  a  rolling  region  extending  30  to  40  miles 
from  the  sea.  In  the  hill  country  the  gravels  usuallj^  take  the  form  of  osars 
or  osar  terraces,  but  when  they  reach  the  broad  valleys  of  gentler  slope 
they  expand  into  great  plains  or  tracts  of  reticulated  ridges.  These  are 
mostly  situated  between  the  contours  of  230  and  600  feet. 

4.  The  forms  of  the  ridges.     In  western  Maine  the  ridges  are  usually 

MON  XXXIV 29 


450  GLACIAL  GRAVELS  OF  MAINE. 

rather  narrow  at  the  north  end  of  the  plexus,  and  have  rather  steep  lateral  • 
slopes.  Groing  southward  we  find  the  ridges  on  the  aA^erage  becommg 
higher  and  correspondingly  massive  till  we  arrive  within  a  few  miles  of  the 
contour  of  23U  feet.  The  ridges  then  grow  broader  as  we  still  go  south- 
ward, the  lateral  slopes  more  gentle,  and  the  hollows  shallower.  In  the 
more  level  country  of  eastern  Maine  there  is  an  analogous  but  less-marked 
change  of  form. 

5.  Their  relations  to  marine  deltas  of  glacial  origin.  All  the  deltas 
left  by  glacial  streams  in  the  sea,  both  the  broad,  fan-shaped  deltas  deposited 
in  the  open  sea  and  the  narrower  ones  left  in  bays  or  broad  channels  of  the 
ice,  end  at  the  north  in  reticulated  ridges  inclosing  kettleholes  and  other 
basins  of  various  sizes  and  shapes. 

6.  Their  relations  to  lacustrine  deltas  of  glacial  origin.  Numbers  of 
deltas  were  deposited  by  glacial  streams  in  lakes  inclosed  wholly  or  in  part 
b}^  ice.  In  the  larger  of  these  the  deltas  are  more  or  less  reticulated 
toward  their  northern  extremities. 

7.  Their  relations  to  overwash  or  frontal  deltas  of  glacial  origin.  In 
the  interior  of  the  State,  as  the  ice  retreated  northward  it  often  happened 
that  the  glacial  streams  poured  out  from  the  ice  front  into  valleys  sloping 
southward.  Their  sediments  spread  out  and  filled  the  valleys  like  the  sedi- 
ments of  Alpine  glaciers.  Their  stones  have  been  worn  and  rounded  by  the 
glacial  streams  more  than  they  could  have  been  worn  by  ordinary  streams, 
and  often  they  were  carried  farther  by  the  glacial  streams  than  by  the  river 
of  the  open  valley  beyond  the  ice  front.  Yet  at  the  place  of  final  deposition 
the  water  was  in  no  Avay  confined  by  ice  and  was  practically  an  ordinary 
river.  These  overwash  or  fluviatile  deltas  of  glacial  streams  sometimes  show 
a  rolling,  uneven  surface  with  shallow  hollows,  but  no  deep  kettleholes  or 
conspicuous  reticulations,  except  in  the  valley  of  the  Androscoggin  River 
between  Grorham,  New  Hampshire,  and  Gilead,  Maine.  The  character  of 
the  alluvium  of  this  valley  is  elsewhere  described. 

8.  The  material  of  the  reticulated  eskers.  In  general,  the  kame  mate- 
rial is  coarser  in  the  hilly  regions  and  becomes  finer  southward.  In  the 
Avestern  part  of  the  State  the  reticulated  ridges  contain  multitudes  of  bowl- 
derets  and  bowlders,  many  of  them  much  rounded,  others  with  only  a 
little  polish,  as  if  carved  by  sand  and  gravel  without  having  traveled  far. 


FOEMATIOX  OF  RIDGES  OF  AQUEOUS  SEDIMENT.  451 

All  over  the  State  the  reticulated  ridges  are  usually  rather  coarse.  In 
western  Maine  the  ridges  ti-ansverse  to  the  general  course  of  the  glacial 
river  are  on  the  whole  rather  finer  in  material  than  the  ridges  parallel  with 
the  course  of  the  river;  but  this  rule  is  not  universal.  Indeed  the  reticu- 
lated kames  seem  to  defy  all  rules. 

9.  Their  internal  structure.  Many  of  the  reticulated  ridges,  especially 
near  the  north  end  of  the  plexus,  have  the  steep  slopes  and  roof-like  top 
characteristic  of  the  pellmell  ridge.  All  the  excavations  in  Maine  which  I 
have  examined  show  more  or  less  distinct  stratification.  No  very  distinct 
layers  can  be  expected  where  the  materials  are  very  coarse,  and  the  thick- 
ness of  the  beds  formed  by  a  single  flood  might  be  many  feet. 

WAYS    IN    WHICH    A    RIDGE    OF    AQUEOUS    SEDIMENT    CAN    BE    FORMED. 

1.  Subaerially,  in  the  way  in  which  streams  carrying  much  sediment 
build  up  delta  channels.  Thus,  the  Mississippi  RiA^er,  the  Po,  etc.,  near 
their  mouths  are  flowing  on  top  of  a  ridge  composed  of  their  own  sediments. 
This  ridge  is  really  composed  of  two  ridges  which  form  the  banks  of  the 
stream,  but  when  the  amount  of  sediment  is  great  the  ridges  coalesce  at  the 
bottom  and  the  river  flows  in  a  depression  on  the  top  of  a  single  broad 
ridge.  They  seldom  rise  very  high  before  the  stream  abandons  the  old 
channel  and  makes  for  itself  a  new  one  at  the  side  of  the  old,  thus  spread- 
ing out  in  the  well-known  fan  shape. 

2.  Wholly  within  channels  of  the  ice,  either  subglacial  or  superficial, 
the  subsequent  melting  of  the  ice  leaving  the  sediments  rising  above  the 
adjacent  ground. 

3.  At  the  sides  of  rapid  streams  where  they  enter  comparatively  still 
water.  A  good  modern  instance  of  this  kind  of  ridge  may  be  seen  at 
Kingman  (see  p.  98).  This  is,  in  fact,  only  a  subaqueous  example  of 
the  same  process  as  that  by  which  a  subaerial  stream  in  its  delta  builds  up 
two-sided  channels.  The  rapid  glacial  streams,  both  subglacial  and  super- 
ficial, would  form  large  ridges  on  each  side  of  them  as  they  entered  the  sea 
or  a  lake.  This  is  well  exemplified  by  the  gravels  near  East  Monmouth 
(see  p.  189). 

4.  When  a  small  stream  bearing  much  sediment  entered  a  body  of 
still  water,  the  two  ridges  formed  at  the  sides  would  soon  coalesce  at  the 


452  GLACIAL  GKAVELS  OF  MAINE. 

bottom,  aud  tlien  the  stream  might,  under  favorable  circumstances,  build 
up  a  single  ridge  having  a  shallow  channel  on  its  top,  an  exaggerated  sub- 
aqueous form  of  the  ridge  built  above  the  sea  by  rivers  at  their  deltas. 
The  buoyancy  of  the  water  would  enable  such  a  ridge  to  have  much 
steeper  slopes  than  if  formed  above  the  water.  As  a  glacial  stream  under 
these  conditions  entered  the  sea  or  a  lake  it  would  naturally,  as  the  flow 
became  less  rapid  in  autumn,  fill  up  the  channel  or  channels  in  which  it 
had  previovisly  flowed,  so  as  to  leave  the  ridge  with  a  broad  flattish  or 
uneven  top,  or  sometimes  even  rounded.  If  such  a  ridge  were  beneath  the 
sea,  the  subsequent  action  of  the  waves  would  round  off  the  summit  to  the 
lenticular  or  rounded  form. 

5.  A  ridge  forms  in  the  lee  of  an  island,  rock,  mass  of  ice,  or  other 
obstruction  situated  in  the  midst  of  a  sediment-bearing  stream.  Such  a 
ridge  has  previously  been  described  as  forming  in  the  Presumpscot  River 
below  a  bridge  pier. 

All  the  above  cases  are  instances  of  the  general  property  of  running 
water  to  drop  its  sediments  as  its  velocity  decreases.  The  distance  to  which 
the  o-lacial  rivers  could  extend  ridges  after  issuing  from  the  mouths  of  their 
channels  depended  on  the  size  and  velocity  of  the  rivers.  At  Litchfield 
Plain  the  different  ridges  become  confluent  and  are  lost  in  the  sand  plain 
within  one-fourth  of  a  mile,  and  at  the  small  marine  delta  in  Amherst  the 
sand  passes  into  clay  within  the  same  short  distance.  On  the  other  hand,  in 
the  larger  deltas  it  is  3  to  5  miles  northward  from  where  the  ridges  become 
confluent  to  where  they  plainly  were  deposited  in  ice  channels.  It  is  diffi- 
cult to  determine  the  line  between  the  ridges  deposited  in  the  sea  in  front 
of  the  ice  and  those  within  channels  near  the  margin,  if  for  no  other  reason 
than  that  the  ice  must  have  been  retreating  while  the  delta  was  forming 
and  the  one  formation  would  follow  and  overlie  the  other  in  the  retreat. 
If  this  retreat  was  for  any  great  distance,  the  later  sands  ought  to  overlie 
the  earlier  gravel  ridges  deposited  near  the  ice  front  of  the  earlier  times. 
Thus  far  I  have  found  no  field  evidence  of  such  an  order  of  deposition, 
and  it  is  doubtful  if  we  can  admit  more  than  1  to  3  miles  of  retreat  Avhile 
the  larger  deltas  were  in  process  of  formation.  In  addition  to  the  retreat 
of  the  ice  front,  we  have  to  consider  also  the  possibiHty  that  the  sea  was  at 
the  same  time  rising  or  falling. 


t 


i 


A.      KETTLEHOLE    IN    MARINE   DELTA;    NEAR    MONROE  VILLAGE 


*^'-*"''%W^$ 


J3.      LAKE    BORDERED   ON    ALL  SIDES    BY   TERRACES   OF   GLACIAL  GRAVEL;    HIRAM. 
The  place  where  the  lake  is  now  situated  was  probably  occupied  by  an  island  of  ice  when  the  gravel  was  deposited. 


RETICULATED  ESKERS  OE  KAMES.  453 

FORMATION    OF    KETTLEHOLES    AND    OTHER    BASINS    INCLOSED    BY    RIDGES 
OR  BY  PLAINS  OF  AQUEOUS  SEDIMENTS. 

I.  Such  hollows  or  basins  may  be  formed  above  sea  level. 

1.  In  the  channels  of  glacial  streams  either  above  or  beneath  the  ice. 
This  conld  happen  if  the  streams  branched  like  rivers  at  their  deltas  and 
subsequently  came  together  again,  or  became  connected  by  cross  channels, 
thus  inclosing  islands  of  ice  or  covering  the  ice  to  an  unequal  depth  with 
sediment. 

2.  In  case  glacial  sediments  are  deposited  on  the  ice  and  in  process  of 
the  unequal  melting  part  of  the  sediment  slides  one  way  and  part  another, 
or  settles  in  channels  of  streams. 

3.  In  the  process  of  delta  formation  where  a  number  of  streams  ai'e 
each  building  up  its  own  ridge.  These  streams  as  they  radiate  outward 
will  here  and  there  meet  or  approach  one  another  and  their  respective  ridges 
will  inclose  basins. 

4.  By  miequal  fliTviatile  erosion  of  previously  deposited  sediments, 
such  as  the  deep  pools  in  the  beds  of  streams  at  the  base  of  rapids  or 
waterfalls. 

5.  B}^  subterranean  waters  in  the  form  of  boiling  springs.  As  the 
waters  boil  upward  they  carry  off  the  finer  matters  of  the  soil  in  suspen- 
sion, and  even  the  matter  contained  in  solution  may  in  time  come  to  have 
geological  importance.  In  some  cases  small  lake  basins  may  have  been 
formed  in  this  way,  such  as  those  near  Fryeburg  and  in  the  upper  Kenne- 
bec Valley. 

6.  By  the  unequal  filling  of  previously  existing  channels.  The  half- 
moon  lakes  of  the  delta  of  the  Mississippi  River  are  instances  of  this  class, 
and  perhaps  some  of  the  small  lakelets  of  the  alluvial  plain  of  the  Kennebec 
River  between  the  Forks  and  Embden  have  the  same  origin. 

7.  By  ice  dams.  Before  ice  gorges  give  way  streams  sometimes  shoot 
out  tlu'ough  them  with  sufficient  velocity  to  erode  deep  holes  in  the  valley 
alluvium.  During  the  flood  which  accompanies  the  breaking  of  the  dam, 
sediments  are  sometimes  deposited  over  heaps  of  ice,  and  the  subsequent 
melting  of  the  ice  blocks  leaves  a  hollow  where  the  thickest  ice  was. 

II.  Such  hollows  or  basins  may  be  formed  beneath  relatively  still  water. 

1.  By  glacial  streams  flowing  into  a  lake  or  the  sea.     Judging  from 

the  ridges  formed-  below  the  dam  at  Kingman,  each  stream  issuing  from  the 


454  GLACIAL  GEAVELS  OF  MAINE. 

ice  into  the  still  water  would  form  a  ridge  on  each  side  of  it,  and  these 
lateral  ridges  would  be  connected  by  a  cross  ridge  at  a  distance  from  the 
mouth  of  the  stream  depending  on  the  size  and  velocity  of  the  stream,  the 
depth  of  still  water,  the  size  of  the  transported  stones,  etc.  This  transverse 
ridge  is  due  largely  to  the  Avhirl  of  the  water  where  the  swift  water  enters 
the  still  water.  If  a  number  of  parallel  streams  of  different  sizes  entered  a 
body  of  still  water,  the  transverse  ridges  would  be  formed  at  different  dis- 
tances from  the  mouths  of  the  streams.  The  restilt  would  be  the  same  if 
a  stream  abandoned  its  former  channel  for  a  new  one.  As  the  ice  melted 
and  the  ice  front  receded,  new  transverse  ridges  would  be  formed  from  time 
to  time.  Perhaps  it  would  describe  the  phenomena  better  to  state  that  the 
two  lateral  ridges  bend  their  courses  so  that  they  unite,  rather  than  to  use  the 
term  "cross  ridge,"  as  if  this  ridge  were  distinct  from  the  lateral  ridg-es,  for 
it  is  only  a  deflection  of  them,  formed  in  a  curve  on  the  outside  of  the  whirl 
where  the  swift  water  is  checked  and  set  to  whirling  by  the  mutual  action  of 
the  still  and  the  rapid  water. 

When  small  glacial  streams  build  up  each  its  own  delta  ridge  beneath 
still  water,  the  radiating  ridges  may  approach  one  another  and  thus  inclose 
basins. 

2.  By  glacial  streams  in  ice  channels  beneath  the  level  of  compara- 
tively still  water.  This  would  more  often  happen  in  case  of  subglacial 
streams.  The  method  would  be  substantially  the  same  as  when  basins  are 
formed  above  the  sea. 

3.  In  the  lee  of  a  broad  obstruction  situated  in  the  midst  of  a  flowing 
stream.  Bars  of  gravel  extend  from  each  side  of  the  obstruction,  which 
ciu've  convergently  so  as  to  leave  a  cresceutic  basin  between  the  coalescent 
bars  and  the  obstruction.  I  have  seen  such  basins  in  the  lee  of  small  islands 
in  the  salt-water  fiords  and  inside  "rivers"  along  the  coast.  In  case  of 
glacial  rivers  entering  lakes  or  the  sea,  this  may  have  been  an  important 
condition  for  the  forming  of  basins. 

4.  By  the  unequal  filling  of  subaqueous  channels.  The  shifting  bars  of 
the  Western  rivers  must  often  leave  portions  of  partly  filled  channels  as  deep 
pools,  which  would  become  kettleholes  or  other-shaped  basins  if  raised 
above  water.  The  terraces  of  valley  drift  are  in  general  very  level  on  the 
top,  showing  that  they  were  deposited  under  very  different  conditions  from 
those  of  the  reticulated  ridges  on  the  alluvial  plain  of  the  Androscoggin 


GEOLOGICAL 


A.      BASIN    CONTAINING    LAKELET    IN    THE    MIDST  OF   A    BROAD   GRAVEL    PLAIN      NORTHERN    PART   OF   WINDSOR 


B      GRAVEL    MESA;   SOUTHERN    PART   OF    CHINA 
The  cirque  conla>ning  the  trees  was  not  eroded  ,   the  gravel  was  deposited  m  practically  ils  ptesernt  condition. 


ORIGIN  OF  GLACIAL  GRAVEL  COMPLEX.  455 

River  above  Gilead  or  the  channel  of  such  a  river  as  the  Platte,  if  it  conlcl 
be  drained  dry. 

5.  Where  large  quantities  of  sediment  are  being  carried  downward  by 
a  rapid  stream,  transverse  bars  naturally  form  across  the  stream,  in  which 
the  grains  or  stones  that  are  behind  pass  to  the  front,  one  after  another,  like 
the  grains  in  a  dune  of  blowing  sand  or  in  a  ripple-mark.  Bars  of  this 
kind,  so  far  as  I  have  observed  them,  are  not  large  enough  to  be  consid- 
ered the  correlatives  of  the  large  transverse  ridg'es  so  common  among  the 
plains  of  reticulated  kames. 

The  influence  of  tides  in  causing  the  formation  of  ridges  and  hollows 
by  checking  the  glacial  streams  has  not  been  formally  included  in  this 
list,  since  it  is  doubtful  how  far  tidal  influence  was  felt  by  them.  Yet  the 
tides  may  in  certain  cases  have  had  some  effect  of  this  kind.  The  tides 
would  help  to  a  horizontal  stratification  of  the  finer  sediments. 

In  1878  I  suggested  in  the  American  Naturalist^  that  certain  ridges 
that  project  like  tongues  from  the  side  of  the  alluvial  plain  of  the  Andros- 
coggin near  the  line  between  New  Hampshire  and  Maine  were  due  to  the 
overflow  of  the  river  in  time  of  flood  into  a  lateral  valley  containing  a  lake 
during  high  water.  It  is  still  a  question  whether  there  is  not  a  particular 
size  of  sediment  fragments  which,  with  a  proper  depth  and  velocity  of 
stream,  will  tend  to  form  an  uneven  bed  covered  by  shifting  bars  and  hol- 
lows, while  if  the  fragments  become  smaller  than  this  the  stream  will  fill 
up  the  inequalities  of  its  own  production  and  flow  over  a  level  plain.  The 
drift  of  the  upper  Androscoggin  Valley  is  perhaps  the  key  to  this  problem, 
if  one  ftuly  knew  how  to  use  the  key. 

ORIGIN    OF  THE    GLACIAL  GRAVEL  COMPLEX  AND    ITS    RELATION    TO    MARINE 
AND  LACUSTRAL  DELTAS.- 

PLEXUS   SITUATED   AT   ONE   END   OF   A   JIAEINE   GLACIAL   DELTA. 

Here  there  is  a  gradual  horizontal  passage  of  sediments  from  coarse  at 
one  end  of  the  delta  to  fine  sand  and  finally  clay,  all  having  the  same  level 
as  the  adjacent  beds.     At  the  end  where  the  coarser  sediment  is,  the  plain 

'  Note  on  the  Androscoggin  gLicier,  Am.  Natnralist,  vol.  14,  pp.  299-302,  1880. 

=  The  theory  that  the  kames  were  deposited  in  the  sea  was  enunciated  in  a  paper  by  Prof.  N.  S. 
Shaler,  in  Proe.  Boston  Soc.  Nat.  Hist.,  vol.  23,  pp.  36-44,  and  to  Professor  Shaler  is  due  the  credit 
of  first  publication.  My  own  views  were  worked  out  independently  by  a  study  of  the  ridges  formed 
below  dams,  as  elsewhere  described. 


456  '  GLACIAL  GRAVELS  OF  MAINE. 

is  alwaj^s  uneven  and  contains  kettlelioles  and  basins  of  various  depths. 
Sometimes  a  few  kettlelioles  or  hollows  in  what  would  otherwise  be  a  rather 
level  plain  are  all  the  signs  of  reticulation  that  we  find.  Here  the  ridges 
are  so  broad  and  plain-like  as  to  obscure  their  origin  as  reticulated  ridges. 
Where  the  reticulated  ridges  are  best  developed  there  is  a  pretty  regular 
gradation  in  the  forms  of  the  ridges.  At  the  landward  side  of  the  delta, 
usually  the  north  and  northwest,  the  gravel  is  coarse  and  the  ridges  are 
high  and  have  rather  steep  lateral  slopes.  The  basins  are  correspondingly 
deep,  and  the  transverse  ridges  are  well  defined.  As  we  go  away  from  the 
place  where  the  mouths  of  the  glacial  rivers  were  the  ridges  become 
broader,  though  still  with  arched  cross  section.  Soon  the  ridges  are  so 
broad  as  to  be  plain-like,  and  so  nearly  coalesce  that  the  kettlelioles  are 
only  shallow  hollows,  and  there  is  a  gently  undulating  plain  of  fine  gravel- 
When  the  area  of  sand  is  reached,  the  plain  becomes  nearly  level  on  top 
and  shows  hardly  a  trace  of  separate  ridges.  The  stratification  is  here 
nearly  horizontal,  and  so  continues  into  the  region  of  clays,  where  all  signs 
of  the  separate  ridges  are  lost.  The  broad  osars  sometimes  pass  into  marine 
deltas  by  only  a  few  reticulations  (as  in  New  Grloucester;  see  pp.  227-228). 

1.  The  existence  of  glacial  potholes  and  the  phenomena  of  the  non- 
continuous  gravels  prove  that  subglacial  streams  existed  in  the  coastal 
region,  and  that  they  were  concerned  in  osar  formation,  as  has  previously 
been  pointed  out. 

2.  But  glacial  marine  deltas  occur  in  the  course  of  the  osars  as  a  reg- 
ular part  of  their  development,  sometimes  more  than  once  in  the  course 
of  a  single  river.  They  mark  epochs  in  the  history  of  the  osar  rivers, 
showing  where  the  ice  front  stood  at  particular  epochs.  They  are  thus 
retreatal  phenomena,  not  changing  the  character  of  the  rivers  in  anj^  '^^J, 
but  merely  the  conditions  of  sedimentation.  If  the  discontinuous  gravels 
were  deposited  by  the  subglacial  rivers,  so  were  the  marine  deltas.  Here 
there  can  be  no  compromise  between  the  rival  subglacial  and  superglacial 
hypotheses.  Superglacial  streams  must  account  for  all  the  coastal  phe- 
nomena, including  the  deltas,  noncontinuity  of  deposition,  decrease  in 
quantity  toward  the  south,  the  petering  out  of  the  streams  near  the  northern 
ends  of  the  "rivers"  or  fiords  of  the  coast,  the  lenticular  shape  of  the 
gravel  masses,  the  underlying  terminal  moraines,  etc.,  or  they  must  be 
ruled  out  of  the  coastal  region  altogether,  except  in  the  subsidiary  form  of 


ORIGIN  OF  GLACIAL  GRAYEL  COMPLEX.  457 

overflow  channels  where  the  subglacial  streams  found  their  tunnels  closed 
and  were  forced  for  a  time  to  rise  into  englacial  or  superglacial  channels. 

3.  The  heaviest  burden  that  the  superglacial  hypothesis  has  to  hear  is 
the  basal  character  of  almost  all  the  kame  and  osar  drift.  By  far  the 
greater  part  of  the  glacial  gravels  is  stratified  and  shows  no  sign  of  having 
been  deposited  on  ice,  where  it  would  have  to  fall  as  the  ice  melted.  It 
has  the  appearance  of  having  been  deposited  on  the  grotmd  where  we  now 
find  it,  and  this  is  the  natural  place  for  subglacial  deposits.  It  remains  to 
be  proved  that  superglacial  streams  can  cut  canyons  or  enlarge  lakes  so 
deep  that  they  penetrate  to  the  bottoms  of  the  ice,  except  near  the  ice 
margin,  where  crevasses  are  strongest.  This  reasoning,  however,  applies 
only  to  deposits  within  channels  in  the  ice.  Beyond  the  ice  front  the  delta 
ridges  of  both  kinds  of  streams  would  manifestly  rest  on  the  till  or  rock 
and  can  be  accounted  for  by  either  hypothesis. 

4.  Some  of  the  marine  deltas  are  very  broad  at  their  northern  ends,  as 
in  the  northern  part  of  Alna,  where  one  ends  in  a  broad  transverse  bar  or 
ridge  showing  no  horizontal  assortment  of  sediments  from  the  center  toward 
the  ends.  In  other  places  there  are  two  or  more  short  ridges  projecting 
here  and  there  toward  the  uoi-th,  as  if  several  streams,  not  one,  had  con- 
tributed to  the  formation  of  the  delta.  But  these  deltas  are  a  part  of  an 
osar  system,  and  except  in  these  places  we  have  no  signs  of  more  than  a 
single  glacial  river.  All  this  is  easily  accounted  for  on  the  subglacial 
hypothesis,  since  those  streams  can  force  new  channels  when  their  old  ones 
are  blocked,  or  they  can  rise  into  englacial  or  superglacial  channels.  But 
how  can  a  single  superglacial  stream,  after  cutting  a  channel  down  or  nearly 
down  to  the  bottom  of  the  ice,  wander  into  other  channels  parallel  to  the  old 
one,  all  of  them  also  cutting  to  the  bottom  of  the  ice,  which  was  consider- 
ably below  sea  level  and  only  a  short  distance  back  from  the  ice  front? 
The  supposed  superficial  streams  would  sometimes  have  to  cut  100  or  more 
feet  beneath  sea  level,  and  yet  abandon  these  channels  for  others,  unless 
we  suppose  that  there  were  more  than  one  superficial  stream  tributary  to 
the  delta;  but  elsewhere  in  the  course  of  the  gravel  system  we  have  proof 
of  only  a  single  river.  The  broad  osar  channels,  including  the  retreatal 
channels  and  lakes  north  of  hills,  the  massive  plains  or  mounds  deposited 
in  glacial  lakes,  also  the  osar  border  clay,  all  point  to  a  rapid  enlargement 
of  a  glacial-stream  channel  or  a  pool  when  once  they  became  open  to  the 


458  GLACIAL  GRAVELS  OF  MAINE. 

•sunlight.  This  makes  it  all  the  moi'e  difficult  to  account  for  the  wandei'ings 
of  a  single  superglacial  river  when  it  has  cut  a  channel  to  the  bottom  of 
the  ice,  or  nearly  so,  and  that,  too,  very  near  the  ice  fi-ont.  The  narrow 
marine  delta  could,  perhaps,  sometimes  be  accounted  for  on  the  superglacial 
hypothesis,  for  the  melting  would  probably  be  most  rapid  near  the  mouth 
of  the  main  river,  thus  prolonging  a  narrowly  deltoid  bay  or  channel  back 
into  the  ice  and  open  to  the  sea  in  front.  Ice  gorges  might  possibly  bar  a 
superficial  channel  so  as  to  cause  an  overflow  into  a  new  channel,  but  it  is 
difficult  to  suppose  that  a  dam  of  loose  blocks  would  last  long  enough  to 
enable  a  new  channel  to  be  cut  to  the  bottom  of  the  ice.  If  we  assume 
that  the  channel  became  blocked  by  the  coarsest  sediment  where  it  entered 
the  sea,  what  are  we  to  do  about  the  sediment  at  the  distal  end  of  the  delta, 
which  evidently  went  over  this  supposed  bar  on  its  way  south? 

On  the  whole,  the  difficulties  of  the  superglacial  hypothesis  are  greatly 
increased  by  the  breadth  of  the  northern  ends  of  some  of  the  marine  deltas 
and  the  certainty  that  they  were  enlarged,  not  by  radiate  transportation  in 
the  sea  beyond  the  ice  front,  but  by  a  single  glacial  river  issuing  from  the 
ice  by  several  mouths,  the  more  distant  being  a  half  mile  or  more  from  each 
other.  How  far  the  flow  of  these  different  streams  was  simultaneous,  and 
how  far  successive,  is  left  an  open  question. 

Usually  marine  deltas  are  a  part  of  the  discontinuous  portions  of  osars; 
hence  often  there  are  intervals  to  the  north  of  them  without  gravels.  Here 
we  have  the  same  problem  of  noncontinuity  as  in  the  case  of  the  other  dis- 
continuous deposits.  Some  of  the  deltas,  perhaps,  began  as  massive  bars  or 
mesas  in  gradually  enlarging  glacial  lakes  into  which  the  sea  subsequently 
advanced  as  the  ice  front  retreated,  after  which  time  the  deltas  proper  were 
deposited. 

5.  Were  all  the  reticulated  ridges  at  the  landward  ends  of  the  glacial 
marine  deltas  deposited  in  the  seal 

As  above  noted,  there  are  sometimes  gaps  in  the  systems  north  of  the 
deltas.  In  these  cases  I  conceive  that  the  rapidity  of  the  streams  was  hei'e 
sufficient  to  keep  their  channels  free  from  sediment.  These  conditions 
probably  prevailed  all  the  way  to  the  ice  fi-ont,  and  in  such  cases  all  the 
reticulated  ridges  were  formed  in  the  sea. 

But  where  long  ridges  extend  northward  from  the  proximal  ends  of  the 
deltas,  especially  complexes  continuing  up  to  considerable  heights  above 


OKIGIN  OF  GLACIAL  GEAVEL  COMPLEX.  459 

the  highest  level  of  the  sea  and  for  20  miles  or  more,  as  happens  in  south- 
western Maine,  the  gravel  was  undoubtedly  being  deposited  in  stream  chan- 
nels in  the  ice  at  a  distance  back  from  the  front  at  the  same  time  the  deltas 
were  forming.  While  the  delta  was  forming  the  ice  would  be  retreating, 
and  the  retreat  of  the  ice  would  uncover  the  ice-channel  ridges,  to  be  at 
once  covered  by  gravels  poured  out  by  the  glacial  streams  which  now 
flowed  into  the  sea  at  some  point  northward.  In  these  cases  I  infer  that 
ice-channel  and  frontal  ridges  are  both  represented  in  this  class  of  marine 
deltas.  The  case  would  be  still  more  complicated  if  the  delta  began  as  a 
glacial  lake  or  broad  channel  deposit.  The  history  of  each  delta  is  to  be  , 
deduced  from  the  local  conditions,  and  probably  in  the  various  delta  com- 
plexes we  have  every  variety  and  combination  of  ice- channel  sedimenta- 
tion, with  that  which  takes  place  in  bodies  of  water  in  front  of  the  ice. 

RETICULATED   EIDGES   AT   THE   PROXIMAL   ENDS   OP   THE   GLACIAL   LACUSTRINE 

DELTAS. 

Elsewhere  are  described  what  appear  to  be  lake  deltas  at  East  Brown- 
field,  in  North  Shapleigh,  in  Unity  and  Thorndike,  in  Dixmont,  in  Newburg, 
and  in  other  places.  Two  or  three  are  possibly  below  the  highest  level  of 
the  sea  and  maj^  be  marine,  or  partly  marine.  All  are  north  of  hills,  where 
fringing  lakes  would  be  formed  during  the  retreat  of  the  ice  down  the 
northern  slopes.  I  see  no  points  bearing  on  their  origin  other  than  those 
applying  to  the  marine  deltas. 

RETICULATED   RIDGES   AS   A   PART   OP   GLACIAL   LACUSTRINE   MASSIVES. 

These  are  the  massive  or  solid  mounds  and  mesas  of  coarse  sedi- 
ments, showing  little  horizontal  assortment,  which  I  assume  to  have  been 
deposited  in  gradually  enlarging  lakes  within  the  ice.  They  sometimes 
contain  hollows  or  kettleholes  and  basins,  inclosed  by  broad,  flattish-topped 
ridges  or  plains.  Some  of  the  basins  may  have  formed  where  the  gravel 
was  deposited  over  masses  of  ice  or  around  ice  islands.  If  deposited  on 
the  ice,  I  infer  that  the  gravel  would  lose  its  stratification  during  the  melt- 
ing of  the  ice.  More  often  probably  the  basins  in  this  class  of  gravels  are 
unfilled  portions  of  the  lake,  left  where  broad  reticulating  ridges  failed  to 
coalesce  completely.  This  sort  of  sedimentation  would  result  from  the 
stream  pouring  into  the  lake  from  different  points,  either  simultaneously 
or  in  succession. 


460  GLACIAL  GRAVELS  OF  MAINE. 

RETICULATED   RIDGES   WITHIN   ICE    CHANNELS. 

Near  Dover  Soutli  Mills  the  Moosehead  Lake  osar  divides  into  two 
branches,  each  not  more  than  100  to  250  feet  wide  at  the  base.  They 
continue  a  few  rods  apart  for  about  a  half  mile  southeastward,  when  they 
unite  to  form  a  single  ridge  which  presently  expands  into  a  broad,  almost 
delta-like  plain  of  sand  and  gravel  near  The  Notch.  Both  ridges  have 
rather  steep  slopes  on  each  side,  and  they  inclose  a  long,  narrow  hollow  or 
ravine. 

I  have  before  described  the  three  small  gravel  plains  in  the  northeastern 
part  of  Monmouth.  They  are  about  one-fourth  of  a  mile,  or  somewhat 
less,  in  diameter.  Each  is  crossed  by  a  central  ra^^ne  flanked  by  terraces 
about  one-eighth  of  a  mile  wide.  My  interpretation  is  that  here  a  rapid 
stream  flowed  into  a  small  glacial  lake,  dropping  its  sediment  on  each  side 
and  leaving  the  ravine  where  its  bed  was.  Can  we  apply  this  interpreta- 
tion to  such  a  case  as  that  at  Dover  South  Mills  ? 

If  a  body  of  still  water  existed  at  each  outer  flank  of  tiie  two  ridges, 
there  ought  to  be  a  broad  flanking  terrace  on  each  outer  side ;  if  swift 
streams,  there  ought  to  be  two  parallel  ridges  outside  of  the  two  existing 
ridges.  The  outer  flanks  of  each  ridge  must,  therefore,  haA'e  been  flanked 
by  ice,  and  we  are  compelled  to  suppose  that  a  single  swift  river  flowed 
through  the  central  hollow  or  ravine,  dropping  a  ridge  on  each  side,  and 
its  size  and  velocity  were  such  for  half  a  mile  on  a  gentle  up  slope  that  it 
was  able  to  keep  its  channel  clear  of  sediment  while  building  up  ridges  on 
each  side  from  10  to  30  feet  in  height.  Now  in  Monmouth  the  central 
ravines,  which  I  infer  mark  the  beds  of  the  streams,  are  not  more  than  20 
feet  deep  in  any  place,  and  generally  are  rather  less  than  10;  their  length 
is  onty  half  that  of  the  ridge  in  Dover,  and  the  beds  consist  of  gravel ;  hence 
in  the  process  of  deposition  it  is  evident  that  the  streams  built  up  a  plain  of 
sediment  beneath  them,  though  the  finer  sediment  passed  out  obliquely  into 
the  bordering  lake.  In  Dover  the  ridges  are  in  places  confluent  at  their 
bases,  but  at  the  deeper  hollows  the  ravine  goes  down  to  the  till,  or  nearly. 
I  leave  the  interpretation  an  open  question  until  other  cases  are  examined. 

At  the  Whalesback,  Aurora,  we  have  two  and  sometimes  three  ridges 
extending  for  3  miles  or  more,  and  nearly  ]3arallel.  In  places  the  hollows 
between  the  ridges  are  filled  with  graA^'el  nearly  to  the  top  of  the  ridges;  in 


EETICULATED  EIDGES  WITHIN  ICE  CHANNELS.  461 

Other  places  the}-  are  so  broad  and  deep  that  they  contain  lakelets  and  must 
reach  very  nearly  to  the  till.  If  we  sujjpose  that  the  central  parts  were 
kept  clear  of  sediment  by  swift  streams,  these  transverse  bars  of  gravel 
connecting  the  main  ridges  are  still  to  be  accounted  for. 

In  southwestern  Maine  we  find  in  the  complexes  large  steep-sided 
ridges  extending  for  long  distances  (1  to  3  miles)  without  noticeable  change 
in  average  size  and  without  becoming  confluent,  except  by  occasional  trans- 
verse bars  or  low  ridges  and  many  terraces.  The  contrast  in  structiu'e 
between  the  ridges  of  the  delta,  which  become  broader  and  more  confluent  at 
their  bases  and  show  horizontal  classification  of  sediments,  and  the  ridges 
of  the  large  plexus,  which  show  little  assortment  of  sediments  but  continue 
for  miles  of  nearly  uniform  sizes  and  with  steep  lateral  slopes,  is  very  great 
indeed.  The  delta  plexus  is  an  intelligible  formation;  why  should  not  all 
these  ridges  broaden  toward  the  south  and  become  finer  in  composition  if 
they  were  all  deposited  in  the  sea  or  other  large  body  of  water?  Think  of 
the  enormous  rivers  required  to  flow  between  two  ridges  50  to  100  feet  high 
and  one-fourth  of  a  mile  apart  and  yet  keep  the  space  between  them  so 
clean  of  sediments  that  the  deeper  hollows  are  100  feet  deep,  alternating 
with  transverse  bars  rising  almost  to  the  tops  of  the  lateral  ridges;  and  all 
this,  too,  without  the  ridges  broadening  or  the  sediments  becoming  finer 
southward  over  distances  as  great  as  the  breadth  of  the  reticulated  plexus 
of  even  the  largest  marine  delta.  The  theory  that  the  reticulated  ridges 
were  formed  by  unequal  deposition  in  open  bodies  of  water  accounts  well 
for  the  plexus  at  the  proximal  ends  of  marine  or  lacustral  deltas,  and  for 
some  of  the  reticulations  in  lakes  or  broad  channels  relatively  small  to 
the  flow  of  the  river,  where  there,  was  no  horizontal  classification  of  sedi- 
ments, or  only  an  imperfect  one,  but  it  breaks  down  in  face  of  the  larger 
complexes  and  those  not  connected  with  deltas,  such,  for  instance,  as  those 
occurring  in  the  course  of  the  osars  on  northern  slopes  and  at  considerable 
distances  from  the  sea.  Here  the  reticulated  ridges  were  often  as  plainly 
deposited  between  ice  walls  as  were  any  of  the  osars. 

Let  us  now  take  the  cj,se  of  the  most  complex  and  best-developed 
plains  of  reticiilated  ridges  to  be  found  in  the  State — those  lying  west  of 
the  Saco  River  in  southwestern  Maine.  They  are  situated  in  a  region  where 
the  rocks  are  mostly  granitic  and  the  till  is  consequently  abundant.  The 
country  is  hilly,  hence  probably  favorable  to  the  englacial  till  getting  up 


462  GLACIAL  GRAVELS  OF  MAINE. 

into  the  ice  to  considerable  distances.  The  region  is  crossed  by  two  series 
of  valleys  nearly  at  right  angles.  The  principal  streams  flow  eastward 
along  one  series  of  valleys,  and  their  lateral  tributaries  flow  north  or  south 
in  the  other  series.  The  larger  gravel  series  extend-  from  north  to  south, 
and  thus  are  constantly  going  up  and  down  hills,  crossing  the  east-and-west 
valleys,  or  following  up  the  north-and-south  valleys  to  a  divide  and  then 
descending  into  another  drainage  basin.  Many  of  the  cols  they  cross  are 
more  than  200  feet  higher  than  the  land  to  the  north.  For  20  or  25  miles 
the  channels  of  these  glacial  rivers  would  for  about  half  their  length  be 
filled  with  slack  water  on  the  northern  slopes  and  in  the  lower  parts  of  the 
valleys. 

As  we  trace  the  gravels  southward  we  find  them  occasionally  taking 
the  form  of  a  broad  two-sided  ridge  with  arched  cross  section,  but  for  most 
of  the  distance  they  have  either  the  form  of  the  broad  osar  terrace  or  that  of 
the  plexus  of  reticulated  ridges.  These  different  developments  alternate  with 
each  other  in  the  course  of  the  same  gravel  series,  proving  that  they  were 
the  work  of  a  common  river  and  are  merely  different  types  of  sedimenta- 
tion. Toward  the  south  the  hills  become  lower  and  the  valleys  broader. 
Here  the  plains  of  reticulated  ridges  widen  and  become  the  prevailing  type 
of  gravels ;  yet  here  and  there  are  small  delta-plains  in  the  midst  of  the 
kame  complex  or  at  their  flanks,  while  here  and  there  the  gravel  forms 
level  plains — osar  terraces.  Often  in  this  district  the  central  ridge  of  the 
plexus  is  ver}^  massive,  rising  50  to  100  feet  above  the  smaller  ridges  that 
cover  the  plain  at  its  flanks.  The  lateral  slopes  of  the  ridges  are  here 
rather  steep  and  the  kettleholes  so  deep  that  in  the  forest  they  are  very 
dark  and  gloomy.  Many  of  them  are  more  than  100  feet  deep.  Still 
going  southward,  we  find  on  the  average  the  ridges  becoming  broader, 
lower,  and  more  plain-like,  while  the  kettleholes  become  shallow.  Not 
far  above  the  contour  of  230  feet  the  ridges  become  confluent,  as  an 
undulating  plain,  which  toward  the  south  becomes  more  and  more  level 
and  the  material  becomes  finer  until  it  ends  in  a  sand  plain  which  in  turn 
passes  into  sedimentary  clay.  The  belt  of  transition  between  the  con- 
spicuously reticulated  ridges  and  the  plains  of  marine  clay  varies  from  a 
half  mile  up  to  2  or  3  miles.  In  the  narrower  north-and-south  valleys  the 
gravels  more  often  take  the  form  of  the  osar  terrace  than  the  plexus  of 


ORIGIN  OF  LARGER  COMPLEXES.  463 

reticulated  ridges,  and  ^vhen  the  latter  is  ^^reseut  tlie  reticulations  are  noi 
so  complex  as  in  broad  valleys  or  on  level  plains.  The  problem  of  the 
reticulated  kames  is,  then,  closely  related  to  that  of  the  bioad  osar.  In 
the  one  case  a  single  channel  became  very  much  enlarged  and  a  continuous 
plain  of  rather  horizontally  stratified  gravel  was  deposited  over  the  bottom 
of  the  whole  broad  channel.  In  the  other  case  the  sediment  took  the  form 
of  a  series  of  two-sided  ridges,  more  or  less  confluent  by  their  bases  or  by 
cross  ridges.  And  there  are  in  a  few  cases  transition  forms  between  the 
two  types,  as  of  a  terrace  or  plain  having  a  wavy  surface.  Furthermore, 
the  same  glacial  river  could  in  different  parts  of  its  course  deposit  both 
these  forms.  We  must  infer,  then,  that  no  special  amount  of  water,  or  of 
increase  or  decrease  in  quantity  of  flow,  was  needed.  The  process  depended 
not  upon  the  stream  so  much  as  upon  the  ice  and  the  other  conditions  of 
sedimentation.  These  conditions  are  so  numerous  that  it  can  with  some 
confidence  be  affirmed  that  the  details  of  the  jirocess  would  vary  in  ditferent 
localities. 

ORIGIN  OF  THE  LARGER  COMPLEXES. 

The  general  process  by  which  the  larger  plains  or  complexes  of  reticu- 
lated ridges  were  formed  appears  to  be  about  as  follows: 

North  of  these  plains  are  regions  of  steep  average  southward  slope. 
The  rapid  streams  (mostly  subglacial  in  southwestern  Maine)  brought  down 
great  quantities  of  sediment  from  the  north.  As  they  reached  the  more 
level  country  their  velocity  became  less  and  the  coarser  sediment  was 
dropped.  In  the  case  of  the  broad  osar  channel  the  deposit  of  sediment 
did  not  proceed  faster  than  the  lateral  enlargement  of  the  channel  and  no 
new  channels  were  formed.  A  broad,  rather  level  and  continuous  plain 
was  deposited  across  the  whole  of  this  channel,  which  was  often  as  broad  as 
the  plexus  of  reticulated  kames  adjacent.  If  the  water  could  flow  into  and 
through  this  broad  cliannel,  producing  a  level  plain,  not  an  uneven  plexus 
of  ridges,  how  can  we  admit  that  the  reticulated  ridges  were  deposited  in  a 
body  of  open  water  as  broad  as  the  osar  channel?  The  osar-plain  or  ter- 
race, it  seems  to  me,  is  the  answer  to  our  questions  as  to  what  would  happen 
in  a  single  gradually  enlarging  broad  channel — not  a  jumble  of  ridges,  but 
a  rather  horizontally  stratified  jjlain.  The  evidence  here  distinctly  favors 
the  hypothesis  that  the  ridges  of  the  complexes  under  discussion  are  not 


464  GLACIAL  GRAVELS  OF  MAINE. 

such  as  were  formed  at  the  sides  of  swift  streams  entering  a  body  of  rather 
still  water,  and  where  the  hollows  between  the  ridges  represent  portions  of 
the  channels  in  which  the  rivers  flowed  or  unfilled  parts  of  the  surface 
which  was  then  covered  by  open  water.  Here  the  ridges  were  in  greater 
part  caused  by  the  filling  up  of  channels  formed  between  ice  walls,  and  the 
hollows  and  basins  represent  ice  which  separated  the  different  channels  or 
lay  beneath  the  sediments  as  they  were  dropped.  The  following  discussion 
assumes  that  these  plains  of  steep-sided  reticulated  ridges,  except  as  they 
pass  into  marine  or  lake  deltas,  were  formed  between  ice  walls  in  most 
cases.  The  gist  of  the  problem  lies  in  accounting  for  the  formation  of  so 
many  new  longitudinal  and  transverse  channels.  Some  cause  must  be 
adduced  for  the  streams  acting  in  this  manner  here  at  the  reticulated  kame 
tracts,  while  elsewhere  they  got  along  with  only  a  single  channel. 

All  the  field  phenomena,  as  we  have  seen,  favor  the  hypothesis  that 
there  Avere  rapid  streams  and  consequently  great  transportation  from  the 
regions  lying  north  of  the  great  complexes  of  reticulated  eskers.  So  also 
all  the  causes  of  sedimentation  combine  to  retard  the  streams  and  cause 
deposition  at  the  areas  of  reticulated  ridges.  Many  of  them  were  in  the 
region  of  backwater  north  of  the  hills.  The  slopes  were  less  steep  thaa 
farther  north.  The  subglacial  drainage  had  been  extended  north  over  the 
area  in  question,  and  many  of  the  subglacial  channels  had  come  to  be  very 
large.  During  each  fall  and  winter  the  existing  channels  would  become 
more  or  less  clogged  with  sediment  brought  down  from  the  steeper  slopes. 
A  time  would  come  when  the  stream  would  no  longer  be  able  each  summer 
to  sweep  away  the  debris  accumulated  during  the  preceding  cold  season. 
At  the  time  of  the  spring  floods  the  water,  under  great  pressure  from 
behind,  would  collect  in  the  tunnels.  If  it  found  transverse  and  longitudi- 
nal crevasses  reaching  deep  down  in  the  ice,  it  would  follow  them  laterally, 
and  thus  in  coui-se  of  time  a  new  subglacial  channel  would  be  formed  par- 
allel to  the  old.  Where  the  new  subglacial  outlets  proved  insufiicient  to 
carry  off  the  waters,  they  would  rise  through  crevasses  and  escape  over 
the  surface.  The  situation  of  many  of  the  larger  plains  of  reticulated 
kames  is  rather  favorable  to  the  formation  of  crevasses,  and  a  large  part  of 
these  overflow  channels  were  probably  subglacial.  But  when  the  summer 
floods  came  and  found  the  old  channels  clogged  the  emergency  was  press- 


ORIGIN  OP  LARGEE  COMPLEXES.  465 

ing.  The  floods  must  find  instant  escape  in  some  way,  and  the  natural 
result  would  be  a  complicated  system  of  surface  channels.  These  supposed 
surface  channels  probably  served  for  the  escape  of  the  waters  only  for  a 
short  time  each  year — during-  the  time  of  highest  floods — yet  they  would 
contain  some  sediment.  Thus  probabl)^  streams  both  above  and  beneath 
the  ice  contributed  to  the  formation  of  such  ridges  as  were  formed  in  chan- 
nels between  walls  of  ice. 

While  it  is  true  that  the  situation  of  the  large  complexes  of  western 
Maine  is  in  general  favorable  to  a  free  flow  of  ice  and  the  production  of 
crevasses,  yet  the  reticulated  ridges  often  do  not  expand  to  fill  a  whole  val- 
ley, as  they  would  if  the  ice  were  so  shattered  that  the  subglacial  waters 
could  freely  pass  along  crevasses  in  any  direction.  They  cross  valleys 
and  go  over  cols  in  a  way  impossible  unless  the  ice  at  the  sides  of  the 
system  formed  solid  barriers. 

These  considerations  bear  on  the  question  whether  the  ovei-flow  chan- 
nels Avere  all  subglacial  Admitting  that  the  huge  central  ridges  were 
deposited  in  subglacial  tunnels,  the  question  recurs  whether  so  many  addi- 
tional channels  could  be  formed  subglacially.  The  answer  depends  on  the 
number  and  arrangement  of  the  crevasses.  If  the  ice  was  solid  at  the  sides 
of  a  clogged  subglacial  channel,  I  see  no  physical  process  whereby  the 
stream  could  form  new  subglacial  outlets.  The  facts  showing  considerable 
solidity  of  the  ice  at  the  sides  of  the  glacial  rivers  are  many.  These  facts 
favor  the  hypothesis  that  a  portion  of  the  overflow  channels  Avere  super- 
ficial. Probably  the  water  would  rise  through  crevasses  onto  the  surface 
only  after  the  ice  had  become  rather  thin.  It  has  been  noted  before  that 
the  transverse  ridges  are  sometimes  composed  of  finer  matter  than  the  main 
longitudinal  ridges.  This  is  consistent  with  the  hypothesis  that  the  former 
were  deposited  in  superficial  channels,  but  the  question  can  only  be  settled 
by  examining  their  stratification. 

During  the  time  of  formation  of  the  kames  tlie  ice  must  in  many 
places  have  been  in  motion.  Many  of  the  plains  have  no  transverse  hills 
in  front  of  them  and  the  ice  motion  could  continue  up  to  the  last.  If  at 
this  time  the  ice  had  power  to  push  forward  subglacial  sediments,  the  trans- 
verse ridges  which  had  to  bear  from  their  sides  the  force  of  the  sea,  ought 
to  be  of  great  breadth  and  of  gentle  slopes,  like  the  lenticular  ridge  of  tilL 

MON  XXXIV 30 


466  GLACIAL  GRAVELS  OF  MAINE. 

The  point  did  not  occur  to  me  while  in  the  field  and  was  not  specially 
studied,  but  I  have  no  note  of  transverse  ridges  having  a  difi^erent  con- 
tour from  the  longitudinal  ridge  adjacent. 

Moreover,  we  must  assume  that  the  ice  front  was  retreating.  When  in 
the  retreat  the  ice  had  receded  to  a  given  jDoint,  the  streams  at  that  point 
were  ready  to  cease  to  be,  as  hitherto,  glacial,  and  were  about  to  become 
frontal.  The  matter  poured  out  from  the  front  of  the  ice  would  overlie 
the  previously  deposited  sediments.  In  the  case  of  a  narrow  subglacial 
channel  changing  to  a  broad  osar  channel,  the  retreat  of  the  ice  would  in 
part  be  equivalent  to  the  gradual  and  recessive  melting  of  the  roof  of  the 
vault,  and  then  the  subsequent  lateral  enlargement  of  the  canyon  thus 
formed.  In  this  case  there  are  two  retreats  to  be  considered — one  of  the 
ice  over  the  channel  and  the  other  of  the  ice  at  the  sides  of  the  channel. 
When,  as  is  true  in  many  cases,  there  is  a  ridge  of  coarse  matter  in  the 
midst  of  the  osar-plain,  we  may  consider  it  deposited  in  a  subglacial  chan- 
nel. There  are  many  ways  in  which  such  a  channel  could  change  to  a 
broad  channel  open  to  the  air.  Perhaps  as  plausible  a  theory  as  any  is  that 
often  the  roof  melted  recessively  northward  at  the  same  rates.  If  so,  the 
matter  of  the  broad  plain  would  be,  with  respect  to  the  receding  subglacial 
stream,  frontal  matter,  and  this  would  account  well  for  its  rather  horizontal 
stratification  and  level  surface.  But  though  frontal  with  respect  to  the  roof 
of  the  subglacial  stream,  it  was  contained  between  walls  of  ice  in  whole  or 
in  part,  and  hence  was  glacial  with  respect  to  the  regions  over  which  the  ice 
had  all  melted. 

Now,  as  in  the  retreat  of  the  ice  as  a  whole  the  glacial  streams  had 
continued  to  pour  out  their  sediments  from  the  ice  front  over  the  previously 
deposited  reticulated  g-ravels,  they  would  at  once  begin  to  fill  iip  the  kettle- 
holes  and  change  the  ridged  to  a  level  plain.  The  fact  that  the  ridges  over 
large  areas  still  preserve  their  individuality  proves  that  but  little  frontal  mat- 
ter was  deposited  upon  them.  This  in  many  cases  can  readily  be  accounted 
for,  and  when  a  good  relief  map  is  obtained  perhaps  all  the  cases  can  be 
explained.  In  the  region  of  southwestern  Maine  under  discussion  the  nortli- 
and-south  series  of  gravels  are  connected  by  a  number  of  east-and-west 
series.  The  latter  probably  date  from  the  last  part  of  the  kame  period, 
when  the  glacial  Avater  could  escape  eastward  by  subglacial  or  englacial 
channels  or  over  the  ice  of  the  valleys  more  easily  than  over  the  hills  to  the 


ORIGIN  OF  LARGER  COMPLEXES.  467 

soutli.  Thus  the  main  supply  of  water  from  the  north  would  be  cut  off 
before  the  ice  at  the  sides  of  the  reticulated  ridges  melted,  aud  in  this 
region  of  short  hills  the  supply  of  frontal  or  overwash  matter  was  small 
and  due  to  local  action.  But  in  the  valley  of  the  Saco  River  from  Hiram 
to  Steep  Falls  the  sedimentary  plain  that  borders  the  river  presents  in  cer- 
tain places  just  such  a  structure  as  would  result  if  reticulated  ridges  were 
subsequently  overlain  by  much  frontal  matter,  at  the  same  time  being  more 
or  less  washed  away  and  reclassified.  The  valley  is  inclosed  by  such  high 
hills  from  Steep  Falls  northwestward  that  there  was  no  late  diversion  of 
glacial  waters  out  of  the  valley,  while  numerous  glacial  rivers  have  left 
gravels  showing  that  they  flowed  into  it.  These  are  true  ice-channel  gravels, 
not  overwash,  and  the  plain  of  the  Saco  is  therefore  an  intermediate  forma- 
tion between  the  frontal  or  overwash  apron  aud  the  reticulated  ridges,  and 
contains  both  of  those  formations. 

One  method  of  the  formation  of  reticulated  ridges  has  been  observed 
by  Professor  Wright  at  the  Muir  glacier  and  by  Professor  Russell  at  the 
Malespina  glacier — one  form  of  the  overflow  gravels  suggested  above.  A 
frontal  or  overwash  sheet  of  gravel  is  first  deposited  over  the  thin  marginal 
ice.  During  the  subsequent  melting-,  channels  are  cut  in  the  ice  beneath 
the  gravel  by  streams,  apparently  of  local  origin,  and  the  overlying  gravel 
tumbles  from  both  sides  into  the  channel,  where  it  is  more  or  less  water- 
washed  and  stratified.  It  is  highly  probable  that  ridges  having  a  pellmell 
internal  structure  often  originated  in  substantially  this  manner,  and  it  is  one 
of  the  means  employed  to  produce  the  mounds  and  hollows  of  the  moraines. 
The  clogging  of  the  mouths  of  subglacial  tunnels  would  bring  the  streams 
to  the  surface  of  the  terminal  slope,  like  those  of  the  Malaspina  glacier, 
when  they  Avould  deposit  on  the  marginal  ice  a  more  or  less  ridged  sheet 
of  gravel,  which  would  become  a  jumble  of  ridges,  mounds,  and  hollows 
during  the  unequal  melting  of  the  subjacent  ice.  But  while  admitting  this 
as  one  of  the  methods  of  the  formation  of  reticulated  ridges  and  kettle- 
holes  not  forming  a  part  of  the  delta  plexus,  I  reg'ard  it  as  subordinate  in 
rank  to  sedimentation  in  connecting-  ice  channels  by  the  great  osar  rivers 
themselves,  for  most  of  these  ridges  are  stratified  and  must  have  been 
formed  basally,  not  on  the  ice.  Where  large  ridges  are  composed  of  coarse 
material  and  are  stratified,  we  can  evoke  only  the  largest  and  most  rapid  of 
glacial  rivers,  not  local  brooks  undermining  sheets  of  clay. 


468  GLAOIAL  GRAVELS  OF  MAINE. 

OSAE   BORDER   CLAY. 

This  interesting  deposit  is  so  fully  discussed  in  connection  with  the 
Anson-Madison  system^  that  little  need  here  be  added.  The  general 
conception  which  I  have  formed  of  it  is  as  follows: 

First  an  osar  was  deposited  in  a  narrow  chamiel,  just  as  the  other 
ridges  were.  This  channel  was  subsequently  broadened  by  lateral  melting 
and  erosion  of  the  ice  so  as  to  become  one-eighth  to  one-fourth  of  a  mile 
wide,  and  in  some  cases  wider.  If  a  large  glacial  river  flowed  in  this  broad 
channel,  an  osar  terrace  was  formed  within  it.  If  the  supply  of  water  was 
small,  its  motion  in  so  broad  a  channel  was  necessarily  slow,  and  even  the 
tine  clay  could  be  precipitated  This  clay  is  as  truly  a  glacial  sediment  as 
the  sand  and  gravel,  yet  the  titles  "eskers"  and  "osars"  have  come  to  be 
applied  to  ridges  of  coarser  matter,  and  hence  I  give  a  special  name  to  the 
plain  of  clay  that  borders  the  central  lidge.  Structurally  I  can  not  dis- 
tinguish it  from  the  plain  of  sand  and  gravel  that  borders  the  central  ridge 
of  the  broad  osar.  The  character  of  the  sediments  depended  simply  on  the 
velocity  of  the  stream  that  flowed  in  the  broad  channel.  The  evidence  is 
conclusive  that  this  border  clay  was  contained  in  a  channel  inclosed  wholly 
or  in  part  by  ice.  This  evidence  is  stated  elsewhere  and  need  not  here  be 
repeated.  The  border  clay  is  found  only  in  level  regions  below  the  eleva- 
tion of  about  400  feet,  and  the  slow  velocity  of  the  water  may  in  several  or 
most  cases  have  been  due  to  the  sea  backing  into  the  channels. 

In  several  places  below  the  highest  sea  level  what  appears  to  be  border 
clay  contains  marine  fossils.  This  is  the  case  unless  reaches  of  clay  depos- 
ited in  the  open  sea  alternate  with  border  clay  in  the  course  of  the  same 
system.  But  the  border  clay  has  in  these  cases  been  covered  by  more  or 
less  clay  deposited  in  the  open  ocean  after  the  melting  of  the  ice  at  the  sides 
of  the  bi-oad  ice  channel.  It  will  require  a  more  detailed  field  examination 
than  I  have  been  able  to  give  these  deposits  in  order  to  determine  what 
proportion  of  the  clay  was  deposited  in  the  open  sea  after  the  melting  of 
the  ice  of  the  whole  region,  and  what  was  left  in  the  bottom  of  broad  chan- 
nels and  formed  long  fiords  by  which  the  sea  penetrated  for  considerable 
distances,  perhaps  several  or  many  miles,  into  the  thin  ice-sheet  of  late  gla- 
cial time.     It  was  in  such  broad  channels  that  the  narrow  marine  deltas  were 

■  See  p.  180;  also  Cliutou  sj'stem,  East  Vassalboro  branch,  p.  170. 


DELTAS  IN  FRONTAL  GLACIAL  LxVKES.  469 

formed.  I  have  no  proof  of  any  sucli  fiords  extending  into  the  ice  that 
did  not  proceed  from  the  broadening  of  the  channel  of  a  glacial  river.  Xor 
is  it  here  assumed  that  they  were  at  all  times  filled  with  salt  water.  They 
were  perhaps  more  nearly  estuarine,  with  brackish  water. 

The  border  clay  is  here  and  there  strewn  with  nonpolished  bowlders 
which  have  typical  till  shapes.  They  must  either  have  been  transported 
by  floating  ice  or  have  dropped  from  glacier  ice.  In  this  case,  as  well  as 
in  that  of  similar  bowlders  in  the  marine  clays,  I  prefer  the  interpretation 
of  floating  ice.  I  can  not  perceive  any  way  of  regarding  these  as  proof  of 
an  advance  of  glacier  ice  after  the  deposition  of  the  clays.  They  do  not 
constitute  a  sprinkling  of  till,  much  less  such  a  sheet  as  would  be  left  if 
the  ice  readvanced  over  the  clays,  or  if  the  border  clay  were  formed  sub- 
glacially.  I  see  no  admissible  interpretation  but  that  the  osar  terraces  and 
the  border  clay  were  both  laid  down  in  channels  open  to  the  air.  The 
angular  bowlders  overlying  the  border  clays  are  found  up  to  400  feet.  In 
part  they  must  be  due  to  floating  ice  of  the  sea,  but  there  must  have  been 
ice  floes  or  little  bergs  floating  in  these  broad  glacial  channels,  which,  as 
they  melted,  dropped  their  burden  upon  the  clay.  Some  of  these  bowlders 
are  8  or  iO  feet  in  diameter. 

The  narrow  marine  deltas,  the  broad  osars,  the  border  clay,  the  broad 
solid  or  plain-like  massives,  all  unite  with  the  lake  deltas  and  the  kames, 
eskers,  and  osars  themselves  to  prove  the  gradual  enlargement  of  the  chan- 
nels and  pools  within  the  ice.  Both  subglacial  and  superficial  streams 
could  not  only  hold  their  own  against  the  inflow  of  the  ice  tending  to  close 
the  channels  but  could  enlarge  them. 

DELTAS  DEPOSITED  BY  GLiACIAL  STREAMS  IIS^  FRONTAL  GLACIAL 

LAKES. 

The  best  examples  are  situated  in  Dixmont  and  Unity  and  are  described 
elsewhere.^  All  are  small,  only  5  or  possibly  in  one  case  10  miles  long. 
Regarding  the  frontal  lakes,  it  is  here  only  necessary  to  remark:  (1)  They 
mark  stages  in  the  retreat  of  the  ice  northward.  (2)  They  collected  between 
the  ice  front  on  the  north  and  hills  situated  to  the  south.  Thus  on  a  small 
scale  they  were  equivalent  to  the  lakes  that  fringed  the  southern  border  of 
the  ice-sheet  in  central  New  York  and  Ohio.     (3)  They  difiFer  in  no  essential 

1  See  pp.  141, 146. 


470  GLACIAL  GRAVELS  OF  MAINE. 

respect  from  tlie  dead  water  that  occupied  the  glacial  channels  north  of  the 
hills,  except  that  they  were  not  confined  within  so  narrow  limits.  (4)  Thus 
far  I  have  not  been  able  to  find  fossils  in  their  sediments.  Maine  is  so  far 
from  the  terminal  moraines  of  southern  New  England  that  it  will  not  be 
surprising  if  it  shall  be  found  that  the  ice  front  retreated  northward  faster 
than  the  land  plants  and  terrestrial  invertebrates  could  advance.  More- 
over, these  organisms  had  just  been  wholly  driven  out  of  New  England, 
unless  possibly  on  a  few  of  the  higher  mountains  and  islands.  West  from 
Staten  Island  the  plants  could  follow  the  retreating  ice  by  the  shortest  lines, 
i.  e.,  at  right  angles  to  the  ice  front.  In  New  York  and  Pennsylvania  it 
would  be  much  easier  for  them  to  accompany  the  ice  in  its  retreat  than 
for  them  to  travel  obliquely  after  the  ice  northward  and  eastward  all  the 
wav  from  New  Jersey  to  Maine.  Prof  B.  K.  Emerson  has  recently  found 
fossils  in  sediments  of  late  glacial  or  earl}^  postglacial  age  situated  in 
central  Massachusetts.  It  would  require  only  a  third  as  long  for  terrestrial 
plants  and  animals  to  travel  to  that  place  as  to  Maine,  and  probably  the 
ice  was  all  melted  before  they  reached  the  latter  place.  If  there  was  any 
retreat  for  these  plants  and  animals  from  the  ice  in  eastern  British  America 
it  has  not  been  reported.  Reference  is  here  of  course  not  made  to  algse 
naturally  inhabiting  snow  and  ice. 

VALLEY   DRIFT. 

VALLEY   DRIFT   OF   PURELY   FLUVIATILE   ORIGIN. 

In  a  country  of  hills  and  rather  level  valleys,  like  most  of  Maine,  the 
surface  Avaters  erode  the  uplands,  carry  their  load  down  the  steeper  slopes 
of  the  hills,  and  then  may  or  may  not  drop  the  coarser  portion  as  they 
reach  the  more  moderate  slopes  of  the  valleys.  In  Maine  the  hills  are 
usually  diversified  by  mmierous  small  lateral  valleys,  sometimes  due  to 
inequalities  in  the  distribution  of  the  till,  but  more  often  to  the  accidents  of 
preglacial  weathering  and  erosion.  Most  of  the  surface  waters  of  the 
uplands  are  thus  soon  converged  into  valleys  and  ravines.  Erosion  by 
surface  waters  must  always  have  been  most  active  in  these  smaller  valleys. 

If  the  deep  sheets  of  alluvium  which  cover  the  bottoms  of  the  broader 
valleys  are  composed  of  material  eroded  from  the  uplands  by  surface 
waters  after  the  melting  of  the  ice,  we  ought  now  to  find  a  system  of 
ravines  comparable  in  volume  to  the  valley  drift.     The  brooks  that  form 


VALLEY  DEIFT  OF  FLUVIATILE  ORIGIN.  471 

on  the  hillsides  have  eroded  channels  in  the  till,  sometimes  10  to  20 
or  even  30  feet  deep,  but  in  g-eneral  they  are  small  and  their  united 
volumes  insig'nificant  compared  to  the  great  sheets  of  valley  drift.  The 
surface  of  the  land  is  such  that  there  never  could  be  a  great  diffused  or 
general  ablation,  but  the  erosion  must  have  been  chiefly  confined  to  the 
hillside  ravines. 

While,  then,  there  must  have  been  considerable  erosion  of  the  upland 
till  since  the  disappearance  of  the  ice,  especially  immediately  after  the 
melting,  while  the  till  was  still  unprotected  by  vegetation  and  the  upper 
till  somewhat  unconsolidated,  yet  this  furnished  only  a  small  part  of  the 
valley  drift. 

The  impossibility  of  thus  accounting  for  the  valley  drift  is  still  further 
emphasized  by  the  relatively  short  time  in  which  this  supposed  erosion  of 
the  uplands  must  have  been  accomplished.  The  upper  stratum  of  the 
valley  drift  often  extends  beneath  the  sea  level  of  that  time  as  deltas 
deposited  by  the  rivers  in  the  sea.  No  matter  what  origin  we  assign  to 
the  valley  drift,  the  great  mass  of  the  deposit  must  have  been  laid  down 
between  the  time  of  the  melting  of  the  ice  at  the  place  of  deposit  and  the 
retreat  of  the  sea  to  its  present  level.  The  limited  erosion  by  the  sea  dui-- 
ing  this  time  proves  it  to  be  geologically  a  very  brief  period. 

Furthermore,  we  must  remember  that  the  till  resists  erosion  far  better 
than  the  sedimentary  drift.  For  a  large  part  of  postglacial  time  the 
streams  have  been  able  to  erode  and  transport  the  sediments  of  the  valleys 
more  rapidly  than  the  upland  erosion.  This  is  proved  by  the  great  size  of 
the  valleys  of  erosion  which  the  streams  have  excavated  alike  in  the  marine 
clays,  in  the  valley  di-ift,  and  in  the  glacial  sediments  proper.  Only  here 
and  there  locally  has  deposition  exceeded  transportation  in  the  lowland 
valleys.  Any  such  relation  of  the  comparative  difficulty  of  erosion  of  the 
till  and  the  sediments,  or  of  land  slopes  to  rainfall,  as  now  exists,  could 
plainly  never  have  caused  the  great  accumulation  of  alluvium  in  the 
valleys.  When  once  the  tenacious  till  was  eroded,  the  streams  would  have 
been  able  to  transpoi't  most  of  the  loosened  matter  direct  to  the  sea.  Only 
the  coarser  matter  would  be  left  in  the  valleys,  and  a  fine  clay,  like  the 
lowest  layer  of  the  valley  drift,  would  be  impossible  under  the  conditions 
assumed. 

Moreover,  we  must  account  for  the  coarse  residual  matter  that  would 


472  GLACIAL  GRAVELS  OF  MAINE. 

be  left  on  the  uplands,  if  there  had  been  so  great  an  erosion  of  the  till  after 
it  had  become  bare  of  ice  that  it  furnished  the  material  for  such  thick  sheets 
of  finer  sediment.  The  till  contains  material  of  all  sizes  from  bowlders 
down  to  rock  flour.  Any  large  erosion  of  the  surface  till,  especially  where 
it  would  largely  be  localized  in  the  smaller  upland  ravines  and  valleys, 
ought  to  have  left  a  mass  of  residual  matter  composed  of  the  bowlders  and 
larger  stones.  This  ought  now  to  be  either  in  the  ravines  of  the  hills  where 
it  would  be  left  when  the  finer  matter  was  carried  away,  or  to  form  alluvial 
cones  in  the  larger  valleys  near  the  mouths  of  the  steeper  hillside  brooks. 
In  the  mountains  such  cones  are  noticeable,  but  they  at  once  show  them- 
selves to  be  composed  of  difiPereut  material  from  most  of  the  valley  drift, 
and  they  add  very  much  to  the  difficulties  of  the  hypothesis  that  the  valley 
drift  is  derived  from  fluviatile  erosion  products.  Conclusion:  Unless  locally 
in  the  mountains,  there  is  no  such  body  of  residual  coarse  matter  left  on  the 
hillsides,  or  as  alluvial  cones  at  the  mouths  of  brooks,  as  testifies  to  any 
great  erosion  of  the  till  since  it  was  deposited  by  the  ice,  still  less  such  a 
vast  quantity  as  would  be  required  by  the  fluviatile  hypothesis.  Indeed, 
the  small  sizes  of  the  brook  channels  of  the  uplands  is  surprising.  I 
have  known  near  the  base  of  Pikes  Peak  a  channel  one-fourth  of  a  mile 
long  eroded  in  a  single  storm  to  a  larger  size  than  many  a  large  perennial 
brook  in  Maine  has  been  able  to  erode  in  all  the  time  since  the  melting  of 
the  ice. 

One  class  of  fluviatile  residual  gravels  here  deserves  further  notice. 
The  larger  streams  and  rivers  have  not  infrequently  excavated  canyons  in 
the  till  or  rock  since  the  melting  of  the  ice.  This  most  often  occurs  in  east- 
and-west  valleys,  where  the  ice  often  left  deep  morainal  sheets  or  ridges 
across  the  valleys.  Here  rapids  and  waterfalls  were  formed.  The  rivers 
excavated  a  channel  in  the  till  barrier  and  carried  the  coarser  matter  down  a 
short  distance  below  the  foot  of  the  swift  water,  where  it  was  left  as  terraces 
of  valley  drift.  The  stones  are  usually  subangular,  and  are  easily  traceable 
in  the  midst  of  the  original  valley  drift.  Such  a  deposit  at  Kingman  is 
elsewhere  described  (see  p.  98).  Now  if  large  rivers  have  left  the  residual 
matter  from  channels  formed  in  the  till,  much  more  ought  the  brooks  to 
show  such  proofs  of  any  large  erosion  of  the  till. 

Another  consideration  is'this:  Most  of  the  east-and-west  valleys  contain 
less  valley  drift  than  uorth-and-south  valleys,  and  it  is  on  the  average  of 


VALLEY  DEIFT  OF  FLUVIATILE  ORIGIN.  473 

finer  composition.  No  reasons  for  greater  fluviatile  erosion  in  one  class  of 
valleys  than  in  the  other,  other  things  being  equal,  have  as  jet  suggested 
themselves. 

The  quantity  of  the  valley  drift  in  valleys  is  very  greatly  dependent 
on  the  positions  of  the  glacial  rivers,  and  is  to  some  extent  independent  of 
the  drainage  surface. 

While,  then,  we  must  assume  a  certain  amovmt  of  rain  wash  and  erosion 
of  till  by  streams  as  having  helped  to  bring  down  sediment  that  is  now  in  the 
valleys,  this  process  can  account  for  only  a  small  part  of  the  valley  drift. 

Was  the  valley  drift  deposited  in  the  sea?  If  so,  it  might  be  under 
the  following  conditions: 

1.  The  valley  drift  was  deposited,  in  part,  by  glacial  streams  pouring 
into  the  sea.  It  is  plainly  a  different  formation  from  the  marine  glacial 
delta  as  ordinarily  developed.  It  is  possible  that  in  narrow  valleys  the 
structure  would  be  modified  by  tidal  wash  and  scour,  yet  I  see  no  way  to 
account  for  the  total  absence  of  the  reticulated  ridges  formed  at  the  land- 
ward ends  of  the  deltas. 

2.  We  may  attribute  the  alluvium  to  erosion  by  the  sea  waves.  If  so, 
the  residual  beach  gravels  left  after  so  much  of  the  finer  matter  was  washed 
away  ought  to  be  recognized,  and  such  are  not  found.  Even  in  the  most 
exposed  coasts  the  till  was  not  all  washed  away.  Still  less  can  we  postulate 
in  the  interior  valleys,  which  the  rise  of  the  sea  would  change  into  land- 
locked fiords,  any  such  erosion  as  the  valley  drift  calls  for. 

3.  Sheets  of  valley  drift  comparable  in  most  or  all  respects  to  the 
valley  drift  of  the  higher  parts  of  Maine  are  found  in  the  vicinity  of  the 
Green  and  the  White  mountains,  and  thence  extend  south  through  northern 
New  England  far  above  any  admissible  or  alleged  former  level  of  the  sea. 
Even  if  we  admit  that  a  part  of  the  valley  drift  is  mai'ine,  it  is  certain  that 
the  larger  part  was  deposited  above  the  sea. 

4.  The  valley  drift  Avas  deposited  in  the  sea  by  ordinary  rivers.  This, 
I  think,  is  true  for  a  portion  of  the  valleys,  but  only  below  the  former  level 
of  the  sea,  say  450  or  possibly  500  feet  in  the  interior  valleys.  This 
structure  will  be  referred  to  hereafter,  and  the  limits  wherein  found. 

I  conclude,  as  the  result  of  this  discussion,  that  the  valley  drift  extends 
above  the  former  level  of  the  sea.  It  is  a  subaerial  formation,  as  a  whole, 
though  it  locally  passes  into  fluviatile  deltas  deposited  by  the  ordinary 
rivers  in  the  sea. 


474  GLACIAL  GEAYELS  OF  MAINE. 

VALLEY    DRIFT    OF    SEMIGLACIAL    ORIGIN. 

The  evidence  that  the  valley  diift  was  derived  from  the  drainage  of 
the  ice-sheet  is  as  follows: 

1.  The  valley  drift  can  not  be  due  to  the  erosion  of  till  after  it  has 
become  bare  of  the  ice,  either  by  meteoric  and  fluviatile  waters  or  by  the 
sea.     We  have  no  other  assignable  origin  than  glacial. 

2.  The  shapes  of  the  stones  of  the  valley  drift  are  in  general  those  of 
the  glacial  gravels  after  they  have  been  rolled  several  miles  by  the  glacial 
streams.  The  stones  are  in  most  cases  much  more  worn  and  rounded  than 
those  contained  in  the  channels  excavated  in  the  till  by  existing  streams, 
except  on  the  steeper  slopes  of  the  mountains.  The  stones  of  the  gravel  of 
the  valley  drift  are  often  as  much  worn  as  stream  gravels  known  to  date 
from  Tertiary  time,  but  this  they  can  not  be,  since  the  stream  gravels  of 
preglacial  age  were  removed  by  the  ice  or  incorporated  with  the  till.  We 
have  no  machinery  for  the  production  of  such  great  masses  of  rounded 
gravel,  acting  within  valley-drift  time,  except  glacial  streams. 

3.  We  find  in  the  valley  drift  here  and  there  masses  of  coarse  matter 
bearing  no  relation  to  the  local  land  slopes.  Now  coarse  matter  collects 
near  the  ice  where  the  subglacial  streams  emerge  from  the  ice.  The 
lingering  of  the  ice  front  at  a  given  place  would  cause  local  accumulation  of 
coarse  matter  near  that  point.  The  occurrence  within  the  valley  di'ift  of  such 
a  mode  of  assortment  of  sediments  as  does  not  depend  on  the  slopes  of 
the  land  requires  us  to  postulate  glacial  conditions.  An  instance  like  this 
is  found  near  North  New  Portland.     (See  p.  1 88.) 

4.  The  last-named  argument  woidd  be  strengthened  if  at  the  same 
time  with  the  local  coarseness  of  material  it  was  found  that  the  body  of 
coarse  matter  formed  a  low  bar  or  ridge  across  the  valley  and  rose  above 
the  level  of  the  valley  drift  both  to  the  north  and  to  the  south  of  it.  This 
is  the  condition  at  North  and  East  New  Portland.  In  various  places  lakes 
within  the  valley  drift  have  probably  been  formed  in  this  manner. 

5.  The  glacial  origin  of  the  valley  drift  would  be  confirmed  if  near 
the  supposed  overwash  plain  of  sediment  terminal  moraines  were  found. 
Such  occur  at  East  New  Portland,  in  the  valley  of  the  Androscoggin  River, 
at  the  State  line,  and  near  the  Katahdin  Iron  Works. 

6.  In  several  cases  an  osar  broadens  southward  and  passes  by  degrees 


DELATIONS  OF  VALLEY  DRIFT  AND  OTHER  DEPOSITS.         475 

into  a  sheet  of  gravel  extending-  across  the  valley  from  side  to  side  and  not 
distinguishable  from  other  valley  drift.  To  the  south  this  does  not  take  the 
form  of  an  osar  terrace  (broad  osar),  but  is  true  frontal  matter,  passing'  by 
degrees  into  finer  sediments  and  finally  into  marine  clays.  Here  the  glacial 
origin  of  the  valley  drift  is  immistakable. 

7.  That  the  valley  di-ift  is  usually  more  abundant  in  north-and-south 
than  in  east-and-west  valleys  appears  to  be  due  wholly  to  the  fact  that  this 
was  the  prevailing  direction  of  the  glacial  streams.  In  other  words,  the 
law  appears  to  be  that  where  the  glacial  streams  were  most  active  there  we 
find  the  most  valley  drift.  This  gives  a  distinctly  g'lacial  facies  to  the  valley 
drift.  The  sizes  of  the  drainag-e  basins,  especially  of  the  smaller  valleys, 
often  bear  no  relations  to  the  quantity  of  the  drift.  This  points  distinctly 
away  from  the  fluviatile  hypothesis  and  toward  the  glacial. 

Summary. — Tliesc  facts  abuudautly  prove  that  overwash  plains  of  glacial 
sediments  formed  in  front  of  the  ice,  and  that  they  are  typical  valley  drift. 
If  the  glacial  hypothesis  thus  accounts  for  that  portion  of  the  valley  drift 
directly  associated  with  moraines,  osars,  and  other  unmistakable  glacial 
phenomena,  we  need  no  other  hypothesis  to  account  for  those  sediments 
that  were  deposited  at  longer  distances  from  the  ice  front  of  that  time,  since 
the  latter  are  what  should  be  expected  on  that  hypothesis. 

RELATIONS  OF  THE  VALLEY  DRIFT  TO  THE  OTHER  GLACIAL  AND  THE 
MARINE  SEDIMENTS. 

Comparing  the  valley  drift  to  the  other  glacial  sediments,  we  find  the 
following  relations: 

Origin. — They  all  were  at  one  time  transported  by  giacial  streams. 

Places  of  deposition. — Doposits  wlthlu  Icc  chauuels  include  all  the  eskers, 
kames,  osars,  and  border  clay  of  the  varieties  elsewhere  described. 

Deposits  poured  out  in  front  of  the  ice  by  the  glacial  streams  include 
the  following:  The  marine  deltas  with  most  of  the  marine  clays  and  sands, 
deposits  in  fringing  or  marginal  lakes,  and  overwash  ajjrons  or  valley  drift 
poured  out  on  land  slojjing  away  from  the  ice  front. 

I  pause  in  passing,  however,  to  note  that  erosion  of  the  till  by  the 
sea  waves  contributed  to  the  marine  sands  and  clays;  so,  also,  water  wash 
from  the  till  contributed  to  the  valley  drift.  But  in  both  cases  the  glacial 
sediments  so  greatly  exceed  in  quantity  the  eroded  till  that  practically  we 
may  speak  of  both  deposits  as  of  glacial  origin. 


476  GLACIAL  GRAVELS  OF  MAINE. 


HISTORICAL   RELATIONS. 


In  a  preceding-  chapter  the  manner  of  the  retreat  of  the  ice  has  been  dis- 
cussed and  the  hues  of  the  front  haA'e  been  marked  on  the  map  (PL  XXXI) 
as  they  are  supposed  to  liave  been  at  various  periods.  The  lines  of  retreat 
seem  to  indicate  not  only  that  the  melting  took  place  from  above  down- 
ward but  that  it  was  most  rapid  at  the  margin.  They  furnisli  no  proof  that 
any  large  bodies  of  stagnant  ice  were  isolated  from  the  main  body  by  the 
melting  of  the  ice  to  the  north  of  it,  unless  the  ice  situated  south  of  east- 
and-west  glacial  rivers  be  so  considered.  Thus,  near  Oxford  there  is  proof 
that,  at  a  time  when  a  broad  plain  of  sand  was  being  deposited,  it  was  kept 
from  spreading  into  Thompson  Pond  by  the  presence  of  ice  in  the  basin  of 
that  lake.  The  valley  of  the  Little  Androscoggin  River  may  at  this  time  have 
formed  an  arm  of  the  sea  from  Oxford  or  Norway  to  Auburn.  (See  p.  225.) 
In  the  Androscoggin  Valley  in  Gilead  and  Shelburne,  New  Hampshire,  also 
in  the  Kennebec  Valley  from  Embden  northward,  and  elsewhere,  the  valley 
drift  often  does  not  spread  into  lateral  valleys.  This  suggests  that  these 
laterals  were  fill,ed  by  ice  at  the  time  the  central  plains  were  being  deposited. 
While  thus  there  are  indications  that  glacial  channels  often  broadened  till 
they  covered  all  the  valleys  in  Avhich  they  were  situated,  and  thus  the  purely 
glacial  sediments  dejaosited  in  channels  back  from  the  ice  front  passed  by 
degrees  into  frontal  bodies  of  overwash,  the  probability  is  that  the  retreat 
of  the  ice  as  a  whole  took  place  from  the  margin  and  the  glacial  stream 
channels  were  bordered  by  ice  until  the  i-etreat  of  the  general  frontal  line 
back  to  that  place. 

1.  In  ^'alleys  containing  osars  the  larger  glacial  rivers  were  already 
established,  draining  areas  5  to  10  or  more  miles  in  width.  The  same  pro- 
cesses that  collected  the  glacial  gravels  with  so  few  visible  ravines  of  erosion 
in  the  ground  moraine  or  till  sufficed  to  accumulate  the  material  of  the  val- 
ley drift  in  the  channels  of  the  glacial  streams.  In  all  cases  the  smaller 
tributary  subglacial  streams  seldom  left  gravels,  except  for  short  distances 
near  the  main  osars.  This  indicates  that  their  channels  were  small  as  com- 
pared to  the  flow  of  water.  Most  of  their  work,  including  tracts  of  erosion 
of  the  ground  moraine,  glacial  potholes,  etc.,  has  been  covered  out  of  sight 
by  the  englacial  till.  In  a  word,  we  have  in  the  glacial  streams  a  machinery 
for  diffused  erosion  without  the  ravines  required  by  the  hypothesis  of  till 
erosion  by  rains  and  streams  after  the  melting  of  the  ice. 


EEf.ATIONS  OK  VALLEY  DEiFT  AKD  OTHEE  DEPOSITS.        477 

The  plienomena  of  delta  or  diverging-  branches  of  glacial  rivers  prove 
that  from  time  to  time  these  streams  found  their  channels  clogged  or  were 
for  some  other  reason  diverted  to  new  channels.  Admitting  that  these  acci- 
dents were  liable  to  happen  at  any  time,  still  I  can  see  no  especial  liability 
of  their  happening  during  the  very  last  of  the  ice  at  a  particular  place 
except  on  accoimt  of  the  rising  of  a  hill  in  front.  Transverse  hills  crossed 
by  glacial  rivers  might  often  force  the  streams  to  escape  either  east  or  west 
after  the  ice  sank  to  the  tops  of  the  hills.  In  continuous  north-and-south 
valleys  containing  gravels  deposited  in  ice  channels  the  retreat  would  cause 
sediments  to  be  carried  beyond  the  ice  front,  where  they  would  overlie  or 
be  mixed  with  the  pi-eviously  deposited  ice-channel  gravels.  Cases  of  this 
sort  of  deposition  are  found  in  the  valley  of  the  Saco  River  for  many  miles 
above  Steep  Falls,  in  the  upper  Kennebec  Valley,  and  elsewhere. 

Where  the  very  latest  conditions  favored  the  formation  of  the  broad 
osar,  the  channel  might  often  continue  to  widen  till  it  extended  across  a 
whole  valley.  The  marginal  part  of  the  plain  of  sediments  that  would 
extend  across  the  valley  might  be  valley  drift,  and  we  should  hardly  be 
able  to  distinguish  it  from  the  osar  terrace  proper.  But  where  we  find  the 
narrow  osars  or  reticulated  ridges  we  could  not  fail  to  distinguish  them  from 
a  later  deposit  of  overwash  matter,  which  would  necessarily  border  or 
overlie  them.  In  general,  it  is  astonishing  to  note  how  suddenly  sedimen- 
tation ceases.  Kettleholes  and  ridges  of  coarse  matter  are  fomid  with  their 
shapes  clearlj^  defined.  Often  there  has  been  but  little  postglacial  erosion 
to  fill  lip  the  bottoms  of  the  kettleholes.  We  must,  therefore, 'account  not 
only  for  the  valley  drift,  but  also  for  its  absence  from  long  reaches  of  the 
osars  and  reticulated  kames  right  on  the  lines  of  glacial  rivers,  where,  on 
the  glacial  hypothesis  of  the  valley  drift,  its  presence  would  be  expected. 

In  many  cases  the  relief  forms  of  the  land  would  naturally  cause  the 
flow  of  a  glacial  river  to  cease  at  a  given  place  before  the  ice  front  had 
retreated  to  that  point.  Thus,  where  the  ice  flowed  over  transverse  hills 
there  Avould  be  local  deflections  of  ice  movement  during  the  last  days  of 
the  ice.  This  would  make  it  increasingly  easy  for  the  subglacial  streams 
to  find  new  channels  east  or  west  along  the  valley  north  of  the  transverse 
hills,  at  the  same  time  that  the  lowering  of  the  level  of  the  ice  would  make 
it  increasingly  difficult  to  maintain  the  flow  south  over  the  tops  of  the  hills. 
Often  we  can  trace  the  new  channels  by  transverse  series  of  gravels.     Thus, 


478  GLACIAL  GRAVELS  OF  MAINE. 

in  the  hills  of  Oxford  and  north  ei'n  York  counties  three  great  north-and- 
south  osar  series  are  connected  every  few  miles  by  transverse  lines  of 
gravels,  several  of  which  follow  the  east-and-west  valleys.  But  in  general 
we  must  suppose  that  the  latest  channels  of  deilection  were  in  use  for  too 
short  a  time  to  become  enlai-ged  sufficiently  to  permit  within  them  the 
deposition  of  gravels. 

For  various  reasons,  then,  the  waters  of  the  longer  osar  rivers  often 
did  not  form  frontal  or  overwash  gravels  in  front  of  the  ice  during  the 
retreat.  If  they  had  continued  to  flow  up  to  the  last,  the  gravels  previously 
deposited  within  channels  in  the  ice  ought  to  have  been  covered  or  flanked 
by  matter  poured  out  in  front  of  the  ice  during  the  retreat.  That  this  did 
not  happen  is  best  explained  by  supposing  the  streams  to  have  been  diverted 
to  new  channels  at  some  time  not  long  previous  to  the  final  melting  of  the 
ice  at  those  places.  Below  the  level  of  the  sea  it  would  facilitate  inter- 
pretation if  we  could  assume  that  some  of  the  rivers  ceased  to  flow  in 
consequence  of  the  pressure  of  the  rising  sea,  also  if  we  could  assume  that 
toward  the  last  the  melting  of  the  ice  in  the  far  interior  valleys  of  the  State 
was  more  rapid  below  sea  level  than  above  it.  This  would  be  equivalent 
to  the  formation  of  bays  of  the  sea  penetrating  into  the  ice  beyond  the 
general  frontal  line,  a  condition  that  would  facilitate  interpretation  at 
Oxford  and  elsewhere.  Such  an  outline  would  not  be  inconsistent  with 
the  lines  of  frontal  retreat  as  set  forth  elsewhere,  but  thus  far  I  do  not 
find  direct  proof  of  it,  unless  through  the  evidence  furnished  in  some  cases 
by  the  osai-  border  clay. 

"2.  The  absence  of  osars  in  nortli-and-south  valleys  proves  that  the 
channels  of  the  glacial  streams  had  not  become  sufficiently  enlarged  to  per- 
mit deposition  within  them.  The  streams  must  have  transported  all  their 
sediments  to  the  ice  front  and  poured  them  out  as  frontal  overwash  or  valley 
drift.  Where  these  streams  were  united  into  one  main  river  we  would  find 
the  coarsest  matter  arranged  along  the  course  of  the  stream,  and  the  sedi- 
ments would  grow  finer  on  each  side.  The  coarser  mass  would  not  have  a 
definite  border  or  arched  cross  section.  Where  there  were  several  glacial 
streams  there  would  be  a  corresponding  number  of  coarser  belts.  Under 
some  conditions  these  might  form  reticulations  and  inclose  lake  basins  and 
kettleholes,  like  those  in  the  valley  of  the  Androscoggin  River  in  Shelburne, 
New  Hampshire.     These  would  often  be  filled  later  by  other  drift,  but 


EELATIONS  OF  VALLEY  DRIFT  AND  OTHER  DEPOSITS.        479 

miglit  survive  in  very  broad  valleys.     In  some  cases  these  reticulated  ridges 
may  have  been  deposited  in  ice  channels  near  the  front. 

Obviously  the  slopes  of  the  land,  the  breadth  of  the  valleys,  the  size  of 
the  streams,  etc.,  would  determine  the  development  of  the  gravels  after 
passing  out  of  the  ice. 

3.  In  numerous  cases  there  are  north-and-south  valleys  or  passes  lead- 
ing southward  to  low  cols  of  transverse  hills.  In  late  glacial  time  they 
contained  lobes  of  ice  which  were  practically  local  glaciers.  Here  we  not 
seldom  find,  a  short  distance  north  of  the  top  of  the  col,  a  short  esker  and 
small  terminal  moraines.  In  a  number  of  such  valleys  there  is  considerable 
sediment  along  the  northern  slope  for  several  miles.  The  most  probable 
interpretation  is  that  a  fringing  lake  formed  between  the  ice  and  the  hill  in 
front,  and  that  the  glacial  streams  continued  to  pour  into  this  during  several 
miles  of  ice  retreat. 

4.  Some  valleys  contain  terminal  moraines  of  considerable  size.  This 
implies  that  the  ice  front  remained  stationary,  or  nearly  so,  for  a  time. 
Such  moraines  are  found  in  the  valley  of  the  Androscoggin  near  the 
line  between  Maine  and  New  Hampshire,  near  East  New  Portland,  and 
elsewhere. 

In  such  a  case  we  ought  to  find  a  very  deep  overwash  apron  near 
where  the  ice  stood  or  paused,  and  it  might  even  form  a  dam  across  the 
valley  and  inclose  a  lake.  From  this  point  the  sediments  would  become 
finer  in  composition  down  the  valley,  and  mig'ht  even  pass  into  the  marine 
clays. 

5.  Some  east-and-west  valleys  do  not  contain  osar  gravels.  Near  the 
end  of  glacial  time  the  waters  of  these  valleys  could  not  escape  southward 
over  the  hills  bounding  the  valleys  on  the  south,  and  the  ice  would  be 
rather  stagnant.  There  is  here  no  direct  proof  showing  the  courses  by 
which  the  local  waters  escaped.  Some  of  them  would  flow  in  subglacial 
channels,  some  might  escape  between  the  ice  and  the  hill  to  the  south,  or 
superficially  or  englacially.  It  has  already  been  remarked  that  such  of  the 
east-and-west  valleys  as  contain  no  osar  gravels,  or  were  simply  crossed 
by  them,  contain  valley  drift  which  is  but  little  waterworn.  This  points  to 
small  local  streams,  mostly  subglacial  and  transverse  to  the  ice  flow.  Such 
directions  would  often  cause  the  streams  to  transport  sediments  into  arms 
of  the  sea  or  into  distant  north-and-south  valleys.     After  the  ice  front  had 


480  GLACIAL  GRAVELS  OF  MAINE. 

retreated  northward  to  the  bottom  of  an  east-and-west  valley,  all  the  sedi- 
ments derived  from  the  drainage  of  the  ice  on  the  north  side  of  the  valley 
would  be  swept  into  the  stream,  which  then  would  flow  in  the  bottom  of  the 
valley  substantially  parallel  with  the  ice  front  of  that  time.  As  the  ice 
retreated  northward  up  the  hill  more  or  less  sediment  would  be  poured  out 
on  the  open  hillside  below  the  ice,  whence  much  of  it  would  be  carried 
down  the  hill  to  the  bottom  of  the  valley. 

6.  In  some  east-and-west  valleys  hillside  eskers  are  found.  These 
were  deposited  by  glacial  streams  that  flowed  down  the  southern  slopes  of 
rather  high  hills  and  left  their  coarser  sediments  on  the  sides  or  near  the 
bases  of  the  hills.  Sometimes  here  they  are  lost  and  the  streams  must 
have  escaped  superglacially  or  in  channels  too  narrow  to  permit  sedimen- 
tation. In  other  cases  this  class  of  gravels  expand  into  deltas  and  finally 
merge  into  the  alluvium  of  their  valleys.  Evidently  this  valley  drift  dif- 
fers in  no  essential  from  that  not  associated  with  the  osar  gravel,  except  that . 
we  can  trace  its  glacial  origin  more  directly. 

RELATION  OF  THE  VALLEY  DRIFT  TO  THE  MARINE  BEDS. 

We  now  approach  a  series  of  phenomena  very  difficult  to  interpret. 
In  a  paper  read  at  the  Boston  meeting  of  the  American  Association  for  the 
Advancement  of  Science,  in  1880,  I  estimated  the  elevation  of  the  sea  in 
the  interior  of  Maine  at  300  to  350  feet.  The  highest  fossils  I  had  been 
able  to  find  in  the  interior  valleys  were  at  215  to  230  feet  in  Palmyra.  I 
had  also  discovered  certain  high  deltas,  as  that  at  Curtis,  Leeds,  that  were 
from  300  to  350  feet  in  elevation.  My  estimate  was  based  on  the  deltas, 
assuming  that  the  higher  marine  beds  were  nonfossiliferous.  Later,  when  I 
discovered  (1885-86)  that  the  elevation  of  the  beaches  along  the  outer 
coast-line  did  not  exceed  200  to  230  feet,  I  became  qtiite  doubtful  where  to 
place  the  limit  in  the  interior.  It  even  seemed  possible  to  interpret  the 
highest  deltas  as  formed  in  lake-like  bodies  that  toward  the  south  opened  on 
land  bare  of  ice,  while  the  basal  clay  of  the  valle3^s  would  on  this  hypothesis 
be  a  form  of  valley  drift  analogous  to  the  loess. 

The  observations  of  Baron  De  Greer,  made  in  1891,  cover  most  of  the 
area  of  the  elevated  marine  beds.  They  make  it  evident,  in  a  way  that 
local  observations  could  not  do,  that  the  apparent  rise  of  the  sea  in  late 
glacial  time  was  due  to  a  general  subsidence  of  the  glaciated  area.     From 


POEMER  HEIGHT  OF  SEA.  481 

observations  in  Maine  alone  I  have  not  felt  justified  in  maintaining  the  subsi- 
dence on  our  coast  and  that  in  the  St.  Lawrence  Valley  as  contemporaneous. 
Accepting  the  general  conclusions  of  De  Greer,  I  assume  that  the  post- 
o-lacial  elevation  of  the  land  in  the  interior  of  Maine  has  been  about  three 
times  that  of  the  coast. 

FORMER    HEIGHT    OF   THE    SEA. 

To  determine  the  highest  elevation  of  the  sea  in  the  valle^^s  of  the 
interior  of  the  State,  we  have  to  depend  on  the  following  means : 

i.  The  elevation  of  fossils.  Possibly  the  time  may  come  when  this 
method  will  be  applicable,  especially  by  means  of  microscopical  examina- 
tions. Thus  far  I  have  found  no  macroscopical  fossils  in  large  areas  of  the 
marine  clays,  and  do  not  find  the  absence  of  fossils  in  the  glacial  marine 
sediments  fatal  to  their  being  deposited  in  the  sea. 

2.  The  elevation  of  raised  beaches.  On  those  portions  of  the  coast 
region  where  the  hills  were  exposed  directly  to  the  surf,  with  few  or  no 
protecting  islands  lying  to  seaward,  we  readily  find  such  beaches.  Even 
near  the  coast  the  presence  of  hills  toward  the  south  that  would  form 
islands  has  often  so  diminished  the  force  of  the  waves  that  the  beaches  are 
inconspicuous  and  are  traceable  with  difficulty.  At  the  time  the  sea  stood 
at  its  highest  elevation  the  interior  valleys  contained  landlocked  bays  or 
fiords  of  the  sea.  In  the  Sebasticook  and  Penobscot  and  others  of  the 
broader  valleys  it  is  possible  that  the  waves  had  sufficient  force  to  leave 
traceable  beaches,  though  I  have  not  traced  them.  But  these  places  are 
not  where  the  valley  drift  meets  the  marine  beds.  These  two  formations 
meet  in  the  valleys  where  the  crooked  fiords  were  usually  less  than  5  miles 
in  breadth  and  where  we  can  not  expect  to  find  distinct  beaches. 

3.  The  projection  of  lines  of  equal  elevation.  By  projecting  the  eleva- 
tions of  the  highest  raised  beaches  on  the  exposed  coasts,  selecting  points 
at  different  distances  from  the  outer  coast  line,  we  find  the  rate  of  differ- 
ential subsidence.  Assuming  this  rate  to  have  been  the  same  over  the 
interior  as  near  the  coast,  we  can  then  calculate  the  positions  of  the  fines 
of  equal  elevation.  Following  this  method,  Baron  De  Geer  calculates  that 
the  isobases,  or  lines  of  equal  elevation,  would  take  the  following  courses: 

*     *     *     An  isobase  drawn  through  points  which  have  been  upheaved  300  feet 
passes  probably  from  near  Niagara  Falls,  by  Albany,  New  York,  and  Augusta,  Maine, 
MON  XXXIV 31 


482  GLACIAL  GKAVELS  OP  MAINE. 

to  Moncton,  New  Brunswick,  whence  it  turns  backward,  running  northwesterly  and 
northerly,  crossing  the  St.  Lawrence  estuary  about  halfway  between  Cai^e  Gaspe 
and  the  Saguenay. 

The  600-foot  isobase  is  probably  to  be  drawn  from  Georgian  Bay  past  the  outlet 
of  Lake  Ontario,  through  the  southern  part  of  the  Adirondacks,  and  thence  east- 
northeast  nearly  to  Moosehead  Lake.  Here  it  makes  an  abrupt  bend  to  the  north 
and  west,  similar  with  the  loop  of  the  300-foot  isobase  at  Moncton,  and  runs  first 
westward  to  some  point  not  far  from  Three  Rivers,  and  thence,  turning  again  north- 
eastward, it  passes  along  the  uorth  shore  of  the  St.  Lawrence  estuary.' 

Manifestly  this  metliod  is  not  complete  until  the  elevations  of  all  the 
traceable  beaches  are  accurately  determined,  and  thereby  the  amount  of 
local  warping,  if  any. 

The  position  of  the  shore  line  in  any  of  the  inland  valleys  would, 
according  to  this  method,  lie  where  the  profile  of  the  valley,  drawn  in  a 
plane  perpendicular  to  the  lines   of  equal  elevation,  intersects  the  hori- 

.        „       zontal  line  markino-  the  old 


i -^     sea  level.     Thus  in  the  dia- 

FiG.Se.— Diagram  illustrating  tlie  Method  of  finding  the  highest  sea  level  iu      gram    tllC     HnC       nc\)     rcpre- 
an  interior  valley,  r•^  i-  n 

sents  the  profile  oi  a  valley 
supposed  to  be  normal  to  the  lines  of  equal  elevation.  At  &  and  c  are 
raised  beaches,  and  the  profile  is  at  these  points  depressed  below  the  hori- 
zontal line  distances  proportional  to  the  heights  of  the  beaches  at  those  points. 
This  determines  the  position  of  the  point  a,  which  marks  the  former  shore. 
4.  The  elevation  of  marine  deltas.  The  deltas  of  the  interior  at  300 
to  350  feet  are  now  interpreted  by  me  as  marine,  but  possibly  this  point 
may  be  disputed.  The)^  certainly  do  not  bear  such  relations  to  the  fossil- 
iferous  clays  as  the  deltas  nearer  the  coast.  But  sheets  of  cla}'  and  sand 
are  found  extending  from  the  deltas  up  to  considerably  higher  elevations,  and 
therefore  under  no  conditions  do  the  deltas  mark  the  highest  level  of  the 
sea.  Indeed,  it  should  be  expected  that  deltas  Avould  be  formed  in  front  of 
the  ice,  often  at  a  considerable  depth  beneath  sea  level.  The  higher  deltas 
are  more  than  100  feet  above  the  highest  fossil  thus  far  found.  Marine  fos- 
sils are  found  in  Lewistou,  Wintlirop,  Norridgewock,  Skowhegan,  Palmyra, 
Unity,  and  other  interior  towns.  The  highest  deltas  are  found  only  a  few 
miles  beyond  the  fossils.  Both  together  constitute  valuable  collateral  evi- 
dence of  the  presence  of  the  sea  in  the  interior  valleys,  but  do  not  give 
the  extreme  limit. 

'Am.  Geol.,  vol.  9,  p.  248,  April,  1892. 


FOEMEE  HEIGHT  OF  SEA.  483 

5.  The  deeper  interior  valleys  now  occupied  by  streams  and  rivers. 
The  main  valleys  are  often  connected  by  cross  or  transverse  valleys  or  low 
passes.  Up  to  the  highest  level  of  the  sea  we  should  expect  these  trans- 
verse valleys  to  have  been  occupied  by  straits  forming-  a  complex  system  of 
reticulating"  channels  surrounding  numerous  islands.  A  corresponding  series 
of  sands  and  clays  would  mark  these  old  channels  or  straits.  Up  to  the 
height  of  these  transverse  plains  of  fine  sediments  it  is  at  least  possible  that 
the  sea  extended.  Yet  it  is  also  possible  that  the  floods  of  rivers  might 
rise  above  the  divides  between  neighboring  valleys,  and  thus  an  overflow 
might  take  place  from  one  to  the  other.  It  thus  becomes  necessary  to  dis- 
tinguish a  possible  form  of  valley  drift  from  marine  beds  before  it  becomes 
certain  whether  the  transverse  plains  of  fine  sediments  mark  the  presence  of 
the  sea. 

6.  The  character  and  structure  of  the  sediments.  This  constitutes 
another  method  of  distinguishing  between  the  valley  drift  and  the  marine 
beds.  Into  the  main  marine  bays  of  the  time  when  the  sea  stood  at  its 
highest  level  poured  large  rivers  which  to  the  north  were  fed  hj  waters  of 
the  melting  ice-sheet.  Above  sea  level  they  were  depositing  valley  drift; 
within  the  sea,  fluviatile  marine  deltas.  Estuarine  deposits  would  form  the 
transition  between  the  two.  The  determination  of  the  points  of  transition 
would  be  rendered  diflicult  by  the  rise  and  fall  of  the  tides,  and  especially 
by  any  general  rise  or  fall  of  the  sea  level  whereby  at  successive  periods 
the  fresh  and  salt  waters  met  at  difterent  places.  If  we  should  find  a  great 
change  in  the  coarseness  of  the  sediments  taking  place  within  narrow 
vertical  limits,  proving  considerable  slowing  of  the  waters  at  that  point, 
and  especially  if  this  were  observed  in  several  valleys  at  the  same  relative 
position  to  the  lines  of  highest  elevation  as  determined  by  observation 
of  the  coast  beaches,  we  should  have  probable  proof  that  the  streams  of 
the  land  poured  into  the  sea  at  those  points.  Thus  far  I  have  not  been 
able  to  apply  the  method  satisfactorily,  in  part  owing  to  the  rarit)^  of 
known  elevations  in  these  valleys.  Where  the  streams  were  large  com- 
pared to  the  breadth  of  the  valleys  it  is  doubtful  if  this  method  can  be 
applied  with  certainty.  The  broader  and  shorter  valleys,  off  the  lines 
of  the  glacial  rivers,  are  the  most  promising  cases  for  the  application  of 
the  method. 

The  following  data  give  approximate  elevations  of  the  highest  shore  in 


484 


GLACIAL  GEAVELS  OF  MAINE. 


several  of  the  valleys.     The  list  could  have  been  considerahly  extended  if 
the  elevations  were  known: 

JElevatioHD  of  seashore  in  valleys  of  Maine. 


Name  of  valley. 


Place  of  liif;hest  admissible  seashore. 


Character  uf  deposit 

passing  into  marine 

fluTiatile  delta. 


Valley  drift. 


Saco 

Presumpscot 

Little  Androscoggin 
Twentymile  River. . 

Androscoggin 

Sandy  River 

Carrabassett  ... 

Kennebec  


Standish,  below  Steep  Falls 

Near  Sebago  Lake 

,  North  Windliam 

South  Paris 

Sumner  and  Buckfield 

Livermore  Falls,  or  Jay 

Farmington 

New  Portland 

Bingham  or  Moscow 


200  to  250 
250  to  260 
250+ 
400 
350? 
375+ 
440+ 
450? 
450  to  500 


The  Kennebec,  because  it  occupies  a  deep  depression  and  penetrates 
far  north  and  west,  is  better  situated  than  any  other  of  the  valleys  for  con- 
taining' high-level  marine  beds.  It  presents  many  difficult  questions  of 
interpretation  which  it  will  require  detailed  study  to  solve.  The  sands  and 
clays  admitted  as  possibly  marine  in  the  above  table  have  heretofore  been 
interpreted  by  me  as  valley  drift  laid  down  at  the  sides  of  a  broadening 
osar.  The  history  of  this  interesting,  because  difficult,  valley  must  largely 
be  left  an  open  question. 

It  has  been  before  stated  that  the  upper  or  rarely  fossiliferous  marine 
clay  passes  up  the  valleys  as  the  basal  layer  of  what  appears  to  be  valley 
drift.  Even  if  we  grant  the  highest  elevations  given  above  for  the  sea,  we 
do  not  reach  the  limits  of  the  basal  clay,  which  in  places  extends  up  to  600 
feet  or  more. 

Probably  the  most  important'  feature  of  the  valley  drift  is  that  the 
basal  layer  is  of  finer  composition  than  the  upper,  at  least  until  we  reach 
the  steep  mountain  valleys.  Sometimes  it  is  a  fine  gray  clay,  at  other  times 
a  silt,  but  almost  always  it  has  a  finer  composition  than  the  gravels  and 
sands  that  overlie  it.  This  condition  extends  considerably  below  the  old 
sea  level  and  is  widely  shown  by  beds  undoubtedly  marine.  The  valley 
of  the  Penobscot  River  west  from  Medway  shows  little  of  the  basal  clay, 


LOWER  STRATUM  OF  VALLEY  DRIFT.  485 

but  there  appear  to  be  local  reasons  for  the  peculiar  alluvial  drift  of  this 
valley,  such  as  its  direction,  its  passing  through  so  many  lakes  that  would 
arrest  its  sediments,  its  large  ravines  or  gorges  of  postglacial  erosion  both 
in  rock  and  till,  with  terraces  composed  of  the  coarser  eroded  matter  extend- 
ing for  some  miles  below  the  gorges,  etc. 

CAUSES  OF  THE  RELATIVE  FINENESS  OF  THE  LOWER  STRATA  OF  THE  VALLEY 
DRIFT  AND  THE  MARINE  BEDS   OF  THE  INTERIOR  VALLEYS. 

The  valley  drift  passes  into  the  marine  beds  by  not  easily  distinguish- 
able gradations.  They  are  here  treated  together  in  order  to  avoid  the 
necessity  of  absolute  determination  or  distinction  of  one  from  the  other  in 
the  field. 

THE    LOWER    STRATUM,    COMPOSED    OF    CLAY,    SILT,    OR   FINE    SAND. 

1.  We  have  already  given  23roof  that  this  sediment  was  chiefly  of 
glacial  origin. 

2.  The  average  composition  of  the  till  is  such  that  great  quantities  of 
fine  glacial  sediment  demand  the  existence  of  great  quantities  of  the  coarser 
matter  also,  although  it  must  be  admitted  that  in  some  of  the  interior 
regions,  as  the  upper  Kennebec  Valley,  the  local  slates  would  cause  the  till 
to  have  a  finer  than  average  composition. 

The  inference  follows  that  at  the  time  the  finer  basal  clays  and  silts 
which  cover  the  bottoms  of  the  valleys  were  being  deposited,  there  was 
also  a  bod}'-  of  coarser  sediments  being  deposited  higher  up  in  the  valleys, 
or  in  part,  perhaps,  in  channels  within  the  ice.  The  smaller  glacial  streams, 
perhaps,  then  carried  little  beyond  the  ice  front  except  Gletschermilch  and 
the  finer  debris. 

3.  Fineness  of  sediment  implies  the  i^resence  either  of  the  sea  or  of  a 
lake,  or,  if  above  their  level,  a  very  gentle  slope.  Some  of  these  basal  fine 
sediments  pass  above  any  level  of  the  sea  that  now  appears  at  all  admissi- 
ble. The  interpretation  is  thus  preferred  that  the  land  slopes  were  very 
gentle  at  the  time  the  basal  fine  sediments  were  deposited.  Such  low 
gradients  must  have  marked  the  time  of  deepest  subsidence  of  the  land, 
and  I  see  no  other  assignable  cause — remembering  that  the  subsidence  in 
northwestern  Maine  was  three  or  more  times  that  of  the  coast,  or,  rather, 
that  the  postglacial  elevation  has  been  such. 


486  GLACIAL  GRAVELS  OF  MAINE. 


THE   COARSER   TIPPER   STRATUM. 


1.  The  fact  that  the  till  was  only  partially  eroded  from  the  outer  islands 
proves  that  the  retreat  of  the  sea  was  geologically  rapid,  especially  if,  as  is 
probable,  the  surf  beat  against  the  ice  all  the  time  of  the  retreat  to  the  sea 
margin  and  only  once  on  the  land  situated  beneath  the  sea  at  its  highest 
level,  and  that  during  the  time  of  elevation  of  the  land. 

2.  While  we  do  not  know  the  amount  of  early  glacial  subsidence,  we 
do  know  approximately  the  amount  of  postglacial  elevation.  I  assume  that 
this  elevation  has  been  about  three  times  as  great  in  northwestern  Maine  as 
at  the  outer  coast  line.  The  moment  this  differential  elevation  began,  the 
gradients  of  the  valleys  leading  southward  became  steeper,  and  grew  more 
and  more  so  during  all  the  time  the  land  was  rising  (the  apparent  retreat  of 
sea)  to  its  present  position. 

3.  Marine  glacial  deltas  are  formed  at  the  ice  front.  The  presence  of 
such  deltas  in  the  interior  of  the  State  within  100  feet  or  less  below  the 
highest  admissible  level  of  the  sea  in  their  respective  localities,  and  that, 
too,  at  elevations  of  about  100  feet  above  the  highest  marine  glacial  deltas 
that  lie  nearest  the  coast,  proves  that  the  ice  still  covered  all  the  northern 
part  of  the  State  at  the  time  the  sea  had  reached  its  highest  elevation,  or 
nearly.  Indirectly  they  furnish  proof  that  the  greater  subsidence  to  the 
north  had  at  this  time  been  already  accomplished. 

4.  The  inference  follows  that  at  the  time  the  sea  reached  its  highest 
level  (i.  e.,  when  the  subsidence  of  the  land  was  arrested)  glacial  sediments 
were  still  being  poured  down  the  valleys  in  front  of  the  retreating  ice. 
Above  the  sea  of  that  time  these  glacial  sediments  formed  valley  drift; 
below  that  level,  fluviatile  marine  deltas.  During  the  differential  elevation 
of  the  northern  lands  this  delta  would  recede  southward  with  the  shore  of 
the  sea.  The  steeper  gradients  would  now  enable  the  coarser  glacial  sedi- 
ments to  be  transported  to  longer  distances  from  the  ice,  where  they  would 
be  deposited  over  the  beds  of  finer  sediments  already  spread  over  the 
bottoms  of  the  valleys.  Moreover,  there  would  be  more  or  less  erosion  of 
the  coarse  sediments  previously  deposited  farther  up  the  valleys  than  the 
basal  clays  extend,  and  the  eroded  matter  would  be  transported  nearer  to 
the  sea  and  often  might  reach  it  and  help  form  a  fluviatile  delta  where  the 
rivers  flowed  into  the  sea. 


UPPER  STRATUM  OF  VALLEY  DRIFT.  487 

As  elsewhere  noted,  these  fluviatile  deltas  can  be  traced  in  all  the 
larger  valleys.  The  delta  of  the  Andi'oscoggiu  reaches  to  the  sea,  or 
nearly,  as  ought  to  be  the  case  where  a  large  stream  continues  to  pour 
sediment  into  the  sea  during  the  whole  time  of  the  retreat.  The  delta  of 
the  Kennebec  covered  not  only  the  basal  clay  of  the  valley  with  coarse 
gravel  and  cobbles  from  Bingham  for  many  miles  southward,  but  also  all 
the  fossiliferous  clays  from  Noi'ridgewock  south  to  a  breadth  of  several 
miles.  From  Madison  south  the  delta  consisted  of  sand;  northward  it 
became  coarser.  The  delta  sand  is  not  traceable  south  of  Waterville. 
The  fluviatile  delta  of  the  Penobscot  is  indistinct  south  of  the  mouth  of 
the  Piscataquis  River.  I  have  not  been  able  to  trace  definitely  the  clays 
which  naturally  belong  to  a  fluviatile  delta  of  sand,  but  undoubtedly  the 
finer  sediments  were  swept  out  to  sea  and  helped  form  the  upper  or 
sparingly  fossiliferous  clays. 

5.  South  of  where  the  fluviatile  deltas  of  the  Kennebec  and  Penobscot 
rivers  disappear  as  broad  sheets  there  are  low  plains  or  lateral  valleys  which 
would  be  covered  by  sea  water  up  to  the  time  when  the  sea  had  nearly 
sunk  to  its  present  level.  If  these  rivers  continued  to  bring  down  the  same 
quantity  of  sediment  as  formerly,  I  do  not  see  why  the  fluviatile  deltas 
should  not  be  prolonged  all  the  way  to  the  sea,  or  at  least  they  should 
spread  laterally  into  these  broader  bays  of  that  time. 

Various  reasons  can  be  assigned  for  these  deltas  failing  to  be  extended 
all  the  way  to  the  sea.  Thus,  as  the  ice  receded  toward  the  north  a  larger 
proportion  of  the  sediment  might  be  dropped  at  a  distance  from  the  sea. 
The  supply  of  glacial  sediments  would  diminish  as  the  ice  melted.  The 
flow  of  water  may  have  diminished  as  the  elevation  advanced.  As  the 
gradients  became  steeper  the  sediment  would  be  carried  out  farther  to  sea 
and  would  tend  less  to  spread  into  the  lateral  bays.  Parts  of  deltas  may 
have  disappeared  by  erosion.  The  net  result  was  that  the  deltas  were 
narrow,  no  longer  extended  back  from  the  rivers,  and  are  hardly  dis- 
tinguishable from  the  flood  plain. 

The  existence  of  Menymeeting  Bay  has  a  bearing  on  the  history  of 
both  the  Kennebec  and  Androscoggin  rivers.  Into  this  large  lake-like  body 
of  water  both  these  rivers  flow.  Both  have  formed  delta  flats  near  where 
they  enter  it.  If  there  had  been  any  such  transportation  of  sediments 
when  the  sea  stood,  say,  30  feet  above  its  present  level,  as  took  place 


GLACIAL  GEAVELS  OF  MAINE. 

while  the  sea  stood  at  high  level,  the  two  rivers  combined  would  have  filled 
up  the  bay,  as  I  conceive.  Yet  the  land  slopes  at  this  time  must  have  been 
almost  as  steej)  as  at  present,  and  were  much  steeper  than  when  the  sea 
stood  at  its  highest  level.  The  conditions  would  be  favorable  to  transporta- 
tion from  up  the  valleys,  yet  the  late  deltas  are  compai'atively  small.  The 
most  reasonable  interpretation  is  that  the  supply  of  sediment  fell  off  greatly 
as  soon  as  the  ice  had  melted. 

SIZES  OF  THE  VALLEY-DRIFT  RIVERS. 

Professor  Dana  postulates  in  the  Connecticut  Valley  a  river  large  enough 
to  fill  all  the  space  between  the  terraces — a  condition  inadmissible  in  Maine. 
The  broad  osars  and  the  uneroded  valley  drift  all  point  to  sedimentation  by 
the  rivers  open  to  the  air,  as  taking  the  form  of  rather  level  plains,  not  as 
high  terraces  bordering  a  deep  central  channel. 

The  hypothesis  that  there  was  a  greater  elevation  of  the  interior  than 
of  the  coast  region  of  Maine  helps  clarify  some  heretofore  very  doubtful 
points  of  interpretation.  At  elevations  extending  from  350  to  450  or  500 
feet  are  plains  of  valley  sediments  up  to  5  miles  in  breadth,  and  in  a  few 
cases  they  are  somewhat  wider.  If  these  great  sheets  are  valley  drift,  they 
demand  very  large  rivers.  But  if  they  are  in  large  part  marine  beds,  i.  e., 
fluviatile  deltas  formed  off'shore  in  bays  or  fiords,  we  do  not  need  so  large 
streams  to  account  for  them.  From  the  sea  margin  back  to  the  ice  these 
rivers  were  dependent,  like  ordinary  rivers,  on  the  annual  precipitation. 
Within  the  ice-covered  area  their  waters  were  glacial.  But  the  drainage 
systems  of  the  ice-sheet  did  not  conform  to  those  of  the  land.  Any  attempted 
comparison  of  the  sizes  of  the  valley-drift  rivers  with  the  present  rivers  must 
take  into  account  the  amount  of  glacial  waters  that  Avas  diverted  from  one  of 
the  present  valleys  by  glacial  streams,  or  that  was  brought  into  it.  Such 
calculations  are  necessarily  difficult.  The  valley  drift  is  more  abundant  in 
valleys  that  once  contained  the  larger  glacial  rivers— that  is  about  all  we 
know. 

Valley-drift  time  was  relative.  In  each  valley  it  lasted  from  the  melt- 
ing of  the  ice  until  the  supply  of  glacial  water  was  all  cut  off.  Whatever 
may  have  been  the  annual  precipitation,  the  flow  of  the  valley-drift  rivers 
was  not  only  that  due  to  this  precipitation,  but  also  that  due  to  the  net 
melting  or  wastage  of  the  ice-sheet. 


SIZES  OF  VALLEY-DRIFT  KIVEES.  489 

Below  Moscow  and  Bingham  the  sedimentary  plain  of  the  Kennebec 
is  from  1  to  6  or  7  miles  wide.  The  overflow  stream  fr-om  Bethel  south- 
Avard  into  Albany  was  a  fourth  of  a  mile  wide  or  more.  This  was  an  over- 
flow of  the  Androscoggin  River.  Even  if  we  admit  the  alluviuni  of  the 
broader  valleys  to  be  fluviatile  marine  deltas,  still  we  need  streams  capable 
of  acting  over  great  breadth  and  with  velocity  sufficient  to  transport  gravel 
and  cobbles.  The  breadth  and  character  of  the  deposits  demand  large 
rivers,  but  I  am  not  prepared  to  submit  a  quantitative  comparison  between 
them  and  those  of  to-da}^  It  is  probable  that  there  was  a  greater  rainfall 
then  than  now,  if  we  correlate  valley-drift  time  with  a  part  of  the  career  of 
lakes  Bonneville  and  Lahontan.  But  we  know  neither  the  cause  of  the 
glacial  epoch  nor  the  cause  of  its  termination.  At  present  I  leave  open 
the  qiiestion  of  the  sizes  of  valley-drift  rivers  as  compared  with  those  of  the 
present  time. 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XXXVIII 


MAP  OF  ANDROSCOGGIN  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 

5        ^         ^  ^  ^         y ^  lip  MILES 

1893 


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MONOGRAPH  XXXIV  PL.  XXXIX 


MAP  OF  AROOSTOOK  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


1893 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XL 


MAP  OF  CUMBERLAND  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 


Scale 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLI 


MAP  OF  FRANKLIN  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 


Scale 


42 


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U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLIll 


MAP  OF  KENNEBEC  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLIV 


MOl^Vl'VILLE 


A        2sr        T         I         C 


MAP  OF  KNOX  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 


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U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLV 


CHINA  /  jj  , 


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MAP  OF 
LINCOLN  AND  SAGADAHOC  COUNTIES  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


1893 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLVI 


MAP  OF  OXFORD  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

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MAP  OF  PISCATAQUIS  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 


1893 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  XLIX 


MAP  OF  SOMERSET  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


1893 


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MONOGRAPH  XXXIV  PL.  L 


MAP  OF  WALDO  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  LI 


MAP  OF  WASHINGTON  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 


Scale 


1893 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  XXXIV  PL.  Lll 


wS/ioo/tna 
y  '-iProulNecTs; 


Wood  Id.  Light 


T"  ORTSMOUTH 


MAP  OF  YORK  COUNTY  SHOWING  LOCATION  OF  GLACIAL  GRAVELS 

Scale 


1893 


INDEX. 


A.  Page. 

Abbott,  deposits  in 63,124-125,400,401 

Acton,  deposits  in 256,  262,  318 

Adirondack  Mountains,  ice  How  in 417 

Agamenticus  Mountain,  features  of 257 

Agassiz,  Louis,  cited 4,  275 

Alaska,  glacial  conditions  in 273, 

280,  296-297.  300,  322,  355-358 

Albany,  deposits  in 249-251, 252, 254, 258, 489 

AlbioD,  deposits  in 165-169,  322 

Alegwanus  River,  deposits  near 74 

Alexander,  osar  in 77 

Allen,  J.  A.,  cited 55 

AUuTiutD,  definition  of 16 

Alna,  ageof  deposits  in 393 

delta  in 457 

deposits  in 168, 169 

Alps  Mountains,  glacial  conditions  in 300,318 

Alton,  deposits  in 124 

Amlierst,  delta  in 452 

eskers  in 117-118,  369 

Amity,  osar  in 80 

Andover,  Mass.,  osar  at 217-218,  220, 358, 424 

Androscoggin  County,  deposits  in 179, 

195-211,  213-215,  222,  22^228 

map  of 490 

Androscoggin  glacier,  moraines  of 274-275 

plate  showing  moraine  of 274 

Androscoggin  Lakes,  deposits  near 216 

Androscoggin  Pond,  osar  near 198 

Androscoggin  River,  age  of  deposits  along 394 

delta  in  valley  of 487 

deposits  along 57, 

59,  63, 192-193,  209-210,  216-235,  323,  356,  381,  474, 478, 484 

potholes  in 325 

Anson,  William,  cited 72 

Anson,  deposits  in 179-181, 400, 401, 468 

Appieton,  age  of  deposits  in 393 

deposits  in 148,155,156 

Argyle,  deposits  in 116 

Arkansas  Valley,  glacial  conditions  in 345-351,356 

Aroostook  County,  deposits  in 73-85, 93-94, 418 

map  of ■ 490 

Athens,  deposits  in 171, 173 

Auburn,  deposits  in 209-210,  225,  381,  476 

figures  showing  esker  in 204, 205 

Augusta,  age  of  deposits  at 393 

deposits  at 171,172,182.183,184 


Page. 

Aurora,  age  of  deposits  in 393 

delta  in 372,  374,  376,  391-392 

deposits  in 88, 108, 114,  284,  318,  335,  430,  432,  460-461 

plate  showing  osar  in 414 

Aybol  Stream,  deposits  along ne 

Ayers  Stream,  osar  along 115-116 


Bailey,  J.  W.,  cited 

Baileyville,  osar  in 

Baldwin,  age  of  deposits  at 

deposits  in ^ 246-248,  254, 

plates  showing  osar  in 

Bancroft,  osar  near 

Bangor,  deposits  near 

Baring,  deposits  in 

Baskahegan  Lake,  deposits  near 

Baskahegan  Stream,  osar  along 

Bath,  potholes  near 

Bauneg  Beg,  features  of 257, 

Beach  gravel,  character  of 

fossils  in 

relation  of  till  to 

Beaches,  elevation  of 

figure  showing  ancient 

occurrence  of  raised 

Beddington,  deposits  in 

osar  in 

Belfast,  deposits  at. .  137, 138-139, 143-145,  318,  321,  323, 

Belfast  Bay,  deposits  near 137,138,144- 

Belgrade,  age  of  deposits  in 

deposits  in 

Belmont,  deposits  near 

Belmore,  James,  aid  by 

Benton,  deposits  in 

Berry,  J".  S.,  aid  by 

Berwick,  osar  in 

Bethel,  deposits  in 248,  249,  252,  356, 

Bingham,  delta  in 

deposits  near 

Bitterroot  Mountains,  glaciers  in .- 

Blackwater  Biver,  deposits  near 

Blanchard,  age  of  deposits  in 

deposits  in 

horsebacks  in 

weathering  in 23, 

Bog  Brook,  figure  showing  osar  along 

491 


394 

334,  439 

244,  2J6 

93-94 

87, 124 
73 


262-263 
41-53 
53-54 


382,  384 
145,  382 


181-185 
144-145 


262-263 
405,  489 


492 


INDEX. 


Page. 

Bonny  Eagle,  deposits  near 255 

Bootbbay  Harbor,  beach  gravel  near 51 

Bowlders,  occurrence  of 284, 333-337 

Bo"wdoiu,  figure  sliowing  esker  in 383 

osarin  186-187 

Bowdoinliam,  deposits  in 55, 171, 172-174 

Bramball  Hill,  Portland,  figure  showing  landslip  at.  232 

Brandon,  Yt.,  deposits  at 27 

Bridgton,  osar  in 244-248,439 

Brighton,  esker  in 173 

Brooks,  age  of  deposits  in 393 

dejjositsin 138,143 

Brownfield,  deposits  in ._  254,  256,  257,  253,  259-260 

plate  showing  osar  in 254 

Brownville,  condition  of  rock  in 7 

deltain 459 

preglacial  deposits  in 28 

Brunswick,  deposits  at 55,  56, 193,  200,  203 

potholes  at 325 

Buckfield,  age  of  deposits  at 394 

deposits  in 212-213.381,439,484 

Buckinan,  J.E.,aidhy 88 

Bucksport,  deposits  in 121 

plate  showing  osar  in 120 

Buckston,  deposits  near 243 

C. 

Calai-s,  deposits  near 87 

Campbell,  F.  I.,  aid  by 88 

Cambridge,  deposits  in 148, 159 

Canaan,  age  of  deposits  in 394 

deposits  in 168,171,172,400 

Canton,  erosion  near G6 

figure  showing  osar  in 442 

osarin 206-210,212,381,442 

Cape  Elizabeth,  deposits  near 215-216 

Carmel,  deposits  in 132,136,380 

figure  showing  osar  in  133 

section  across  osar  in 132 

Carrahassett  Valley,  deposits  in 180,  356, 401,  405, 484 

Gary  Plantation,  osar  in 75,  80 

Carys  Mills,  osarin 74-75 

Casco,  osar  in 235-238 

plate  showing  deposits  in 34 

CenterTille,  deposits  in 90, 1)1 

Chaleur  Bay,  deposits  near  92,113 

Chalmers,  E.,  cited 50,70,295,418 

Chamberlin,  T.  C,  cited 14, 266, 280,  284, 431, 446 

letter  of  transmittal  by xii  i 

quoted 359 

Channels,  enlargements  of 317-319 

formation  of 308-317 

Charleston,  gravel  in 129, 131 

.  Charlotte,  deposits  in 73 

Cherryfield,  erosion  near 65 

Chesterville,  osar  in 196-200,  381 

China,  deposits  in 165-109 

plate  showing  deposits  in 168 

I)late  showing  mesa  in 454 

Clarke,  E.  P.,  aid  by 373 

Clay,  character  and  deposition  of 54-58, 170, 180, 408-469 

Clay,  N".  T.,  delta  in 401 

Clifton,  delta  in 391-392 

deposits  in : 119-120 

plate  showing  osarin 120 

Clinton,  deposits  at 168, 171, 172,  380,  382,  429,  468 


Page. 

Coastal  region,  deposits  of 379-413 

Cody ville,  age  of  deposits  at 393 

deposits  near 77,79,83 

Colorado,  glacial  conditions  in 338-351 

sedimentation  in 17-18 

Columbia,  deposits  in 88-90, 

101, 110-112,  320, 388,  406,  425,  434, 437-439 

erosion  near 05 

Columbia  Falls,  deposits  in 88-90,  94 

Connecticut  Yalley,  glacial  river  in 488 

Couway,  N.  H.,  age  of  deposits  near 394 

deposits  near 256,263, 149 

Corinna,  age  of  deposits  in 394 

deposits  in 139-142,  423 

Corinth,  figure  showing  deposits  in 380 

osarin , 129,131 

Cornish,  deposits  in 256,  257 

Corn  ville,  age  of  deposits  in 394 

osarin 171.400 

Cove  gravel,  occurrence  of 41-53 

sections  of 42,45 

"Crag  and  tail,"  phenomena  of 31,308,352-353 

Crawford,  deposits  in 86-88 

Crevasses,  formation  of 310-316,  323-324,  401-402 

CroU,  iTames,  cited 306 

Crooked  Eiver,  deposits  along 249-253 

Crystal,  deposits  in 96 

Cumberland,  deposits  in 229-232,234 

Cumberland  County,  delta  plains  in 374,  375, 3S7 

deposits  in 95,  189-195,  200-201 ,  215-248,  255 

map  of 490 

Curtis,  deltas  at 480 

D. 

Dana,  J.  D.,  cited 3,  28,  54,  67,  68,  328,  329, 424,  488 

Danforth,  osars  in 77,82,83,439 

tillin  430 

Darling,  A.  J.,  aid  by 95 

Dead  Pdver,  deposits  along 187-188 

Deblois,  age  of  deposits  in '. 393 

del tas  in 374, 381 

deposits  in 101, 110-111, 114,  284,  406,  432 

erosion  near 65 

Dedham,  deposits  in 121 

Deering,  age  of  deposits  in 393 

De  Laski,  John,  cited 3 

Deltas,  deposition  of  ..* 321,469-470 

elevation  of 482 

relations  of 455-459 

Denmark,  deposits  in 245, 246, 252 

Dennys  River,  deposits  near 78 

DennysviUe,  age  of  deposits  in 393 

osarin 79 

Detroit,  deposits  in 146,380 

plate  showing  osar  in 146 

Desler,  age  of  deposits  in 394 

deposits  in 139 

Dixmont,  age  of  deposits  in 393 

deltas  in 459,469 

kames  in 146-147 

osarin 140-142,310,423 

Dover,  Me.,  delta  in 435 

osar  in 400,  460 

Dover,  M".  H.,  deposits  at 203 

Dresden,  deposits  in 171 

Drift,  character  of 14,265,470^89 


INDEX. 


493 


Drift,  definition  of 

forms  of 

stratification  of 

transportation  of 10-22, 

(See  also  Valley  drift.) 
Drumlins,  formation  of 

occurrence  of 

Durango,  Colo.,  moraine  near , 

Durham,  deposits  at 57,59,201- 

plate  showing  deposits  in 

Dyer  Plantation,  osar  in 

Dyers  River,  deposits  along 


Eel  Ki ver,  deposits  on 

East  Bowdoinham,  deposits  at 

East  Branch,  of  Penobscot  River,  osar  near  . 

Eastbrook,  deposits  in 

East  Brownfield,  delta  at 

East  Lebanon,  osar  at 

EratLivermore,  osar  in 

East  Machias,  deposits  at 

East  Machias  River,  depo.sits  near 

East  Mancos  River,  moraines  along 

East  Monmouth,  deposits  near 

East  JS'ewport,  osar  at 

East  New  Portland,  deposits  near 

moraines  near 

East  Troy,  kames  in 

East  Vassalboro,  deposits  in 

Edes  Falls,  deposits  at 

Edin  burg,  deposits  in 


10,16 
22-26 


431-4^2 
280-282 


342-343 

■205,  227 


262-263 
196, 199 


86,87 

3C9 

379,  451 

139-140 

356, 474 

419,479 

142 

46S 


Edn 


Qds 


Effingham.  N.  H.,  deposits  near 

Ellsworth,  eskers  near 

Embden ,  deposits  in 179- 

Emerson,  B.  K.,  cited 

Emmons,  S.  F.,  cited 

Enfield,  drift  in 

osar  near 

plate  showing  osar  near 

Englacial  debris,  quantity  of 

Englacial  streams,  action  of ■■ 

courses  of 297-301, 

Epping  Corner,  deposits  near 

Erosion,  definition  of 

Eskers,  definition  of 35, 

features  of 361-369, 

Estes  Park,  glaciers  in 

Etna,  deposits  in 135- 

Exeter  Mills,  deposits  at 

section  across  osar  at - 


108 
275-277 
296-297 
308-310 
111,112 
27 
359-360 
448-467 
350-351 
■136, 141 
132, 427 

133 


Fairfield,  deposits  iu 171 

Falmouth,  deposits  in 229,  231,  232 

Farm  Cove,  gravels  near 92-93 

Farmiugton,  deposits  in 362,  484 

Fayette,  osar  in 196, 198 

Forest,  till  near 430 

Fossils,  elevation  of 481 

occurrence  of 53-5-1,  56,  286-291 ,  374,  379-382 

Franklin,  deposits  iu 117 

FrankliuCounty,  deposits  in....  187-189,  196-200,205-206,210 

map  of 4!»0 


200-201,  369-370,  379 


Freeport.  deposits  in 

Frontal  retreat  of  ice,  map  showing 392 

effects  of 390-394,  401-403 

Fryeburg,  deposits  in 252-253,  256,  258,  261 

Fuller,  C.  B.,  aid  by 53 

cited 287 

G. 

Gardiner,  deposits  at 55, 171, 172 

Gardner,  John,  aid  by 95 

Gardners  Lake,  kame  near 85 

Garland,  delta  in 435 

deposits  in 126-128,330,430 

erosion  in 297 

G eer,  Gerard  de,  cited 480-481 

quoted 481-482 

Georges  River,  deposits  along 147-148, 

154-157,  361,  384,  391,  430 

Georgetown  Island,  potholes  on 325 

Gilbert,  G.K.,  cited 47,400-401 

Gilead,  deposits  in 356,  450, 476 

plate  showing  moraine  in 274 

Glacial  period,  precipitation  during 292 

Glacial  streams,  action  of 291-292 

size  of 292-294 

Glaciers,  drift  fonns  due  to 25 

transportation  of  soil  by 20-21 

Glaciology  of  Maine,  chronological  list  of  publica- 
tions on - 2-4 

Glenroy,  Scotland,  raised  beaches  at 300 

Gloucester,  deposits  in 214 

Goldan,  Switzerland,  landslide  at 10 

Gorham,  Me.,  ago  of  deposits  in 393 

deposits  in 237,  243,  244 

Gorliam,  N.  H.,  deposits  near 210,  216,  248,  356,  405,  450 

Grand  (Schoodic)  Lake,  osars  near 92,  93-94 

Grand  {St.  Croix)  Lake,  bowlders  near 75, 335 

osar  near 75-76 

Gray,  age  of  deposits  in 393 

deposits  in 227-230,  232,  234,  238 

Great  Aletsch  glacier,  action  of 300 

Greene,  deposits  iu , 197,  200, 201 

Greenbush,  age  of  deposits  in 393 

deposits  in 107, 114.  318,  320, 427 

Greenfield,  age  of  deposits  in 393 

delta  in 374, 391 

deposits  in 107, 108, 114 

Greenland,  glacial  condition  of ; 264, 

269-270. 273,  294-295,  308,  322,  439 

Green  Mountains,  direction  of  ice  flow  iu 417 

Greenwood,  deposits  in 233 

Guilford,  deposits  in 126,  400, 401 


Hague  s  Peak,  glacier  on 351 

Hallett  glacier,  character  of 351 

Hallowell,  deposits  in 171, 172 

Hamlin,  C.  E .,  cited 4 

Hammond,  J.  H.,  aid  by 263 

Hampden,  deposits  in 122-125,131,134,136 

figure  showing  deposits  in 381 

Hancock,  deposits  in '  1 20 

Hancock  County,  deposits  in 92, 117-122 

map  of 490 

Harmony,  age  of  deposits  in 393 


494 


IIS'DEX. 


Page. 

Harmouy,  deposits  in 148,159,171,173 

Harpswell,  deposits  at 57 

Hartford,  esters  in 210-211 

Hartland,  clay  near 172 

deposits  hi 173 

erosion  in 429 

osarin 148,152,156,173 

Haycock,  S.  W. ,  aid  by 95 

HayuesTille,  osar  in 81, 84 

Hebron,  kames  in 214 

plate  showing  esker  in 214 

Hermon,  deposits  in 130-133,  427 

section  across  osar  in 133 

Hermon  Pond,  figure  showing  deposits  at 380 

Hersey,till  in 430 

Hiram,  deposits  in 245, 254, 257, 259-260, 467 

plate  showing  deposits  in 258, 452 

Hitchcock,  C.  H .,  cited 2, 

3,  6,  32,  41,  50,  54,  63,  68,  242,  236-287,  295, 360 

quoted 74, 187 

Hitchcock,  Edward,  cited 424 

Hodgdon.osar  in 75 

Hogback  Mountain,  erosion  near 430 

figure  showing 153 

map  of 151 

osars  near 152-154, 157, 331 

Hogback  Mountain  Pass,  plate  showing 152 

plate  showing  osar  at 154 

Holden,  deposits  in 121-122 

Holmes.  Ezekiel,  cited 3 

Hoist,  E.,  explorations  of 269 

Houlton,  osar  near 73,  77,  80 

tiUin , 430 

Howland,  deposits  in IDS,  116, 135,  334 

Huntington,  J.  H.,  cited 3, 233 

I. 

Ice,  map  showing  frontal  retreat  of 392 

retreatal  phenomena  of 390-394 

Icebergs,  drift  forms  due  to 25 

transportation  of  soil  by 21 

Ice  floes,  drift  forms  due  to 25 

transportation  of  soil  by 2 1-22 

Idaho,  glacial  conditions  in 351-355 

Indian  Kidge,  Mass.,  features  of 358 

structure  of 424 

Interglacial  period,  possibility  of 284-291 

Irouton,Colo.,  deposits  at 342 

Island  Falls,  deposits  in 81 ,  84-85,  96 

Isle  au  Haut,  beach  gravel  on 48 

Isobases,  courses  of 431^82 

J. 

Jacksoij.C.T.,  cited 1.-2,6,41,54,63,68 

Jackson,  eskers  in 138 

Jay,  age  of  deposits  in 394 

deposits  in 205.  210,  4S4 

plale  showing  esker  in 214 

Jefferson,  deposits  in 163-164 

Jerusalem,  deposits  in 187-188 

Jo  Merry  Lake,  osar  near 134 

Jonesboro,  age  of  deposits  near 393 

deposits  in 8S-90, 91, 94, 112 

•Tonesport.  ase  of  deposits  near •      393 

deposits  in 320,  382,  388 


K.  Page. 

Kames,  definition  of 35,  359 

features  of 368-369, 448-467 

formation  of 330-333 

Katahdin  Iron  Works,  age  of  deposits  at 394 

deposits  at 134-135,419,474 

rock  weathering  at 8 

Katahdin  osar,  course  of 104, 117, 284,  372, 374 

features  of 335,  381,  400, 430,  432 

plate  showing 108 

Kenduskeag.  deposits  in 128,131,132 

Kenduskeag  Valley,  figures  showing  deposits  in 132 

Kennebago  Valley,  age  of  deposits  in 394 

kames  in 233 

Kennebasis  Eiver,  deposits  near 91 

Kennebec  Bay,  section  across  moraine  near 51 

Kennebec  County,  deposits  in 165-174, 

177-179, 181-187. 189-195 

map  of 490 

Kennebec  Valley,  age  of  deposits  in 394 

composition  of  till  in 485 

delta  in 487 

deposits  in 56, 

57,  63,  64, 171-179, 181, 185-186, 323,  400,  476-478,  484,  489 

potholes  in 327 

section  across 176 

Kettleholes,  features  of 406 

formation  of 453-455 

Kettle  moraine,  features  of 398 

Keystone.  Colo.,  moraine  near 344 

Kezar  Brook,  deposits  along 252-253 

Kibby  Stream,  age  of  deposits  along 394 

horseback  near 187 

Kingman,  deposits  in 60, 

97-100, 102,  381,  425.  434,  437-439,  451,  453-454,  472 

Kingsbury,  esker  near 173 

Knox,  erosion  near 66 

Knox  County,  deposits  in 147-148, 160-163 

map  of  --- 490 

Kossuih,  deposits  in 93 

L. 

Lagi-ange,  age  of  deposits  in 393 

osarin 123-124,400 

Lake  Auburn,  fossils  near 374 

.  Lake  Bonneville,  ITtah,  beach  gravel  near 47 

conditions  at 489 

Lake  Ivanboe,  moraine  near 349 

Lake  Lahontan.^ev.,  beach  gravel  near 47 

conditions  at-- 489. 

Lamoine,  age  of  deposits  at 39.'^ 

deposits  in 119-120 

Landslips,  transportation  by 10-11 

drift  forms  due  to 25-20 

La  Plata  Mountains,  glacial  conditions  in 338-340 

Las  Animas  Valley,  glacial  conditions  in 340-343 

Lead  Mountain,  deposits  near 392 

Leadbetter  Falls,  horseback  at 187 

Lead ville.  Colo.,  deposits  near 345-346,  348 

Lebanon,  osar  in 262-203 

Leda  clay,  occurrence  of 55 

Lee,  L.  A.,  cited 56 

Lee,  deposits  in 99, 103-104 

plate  showing  deposits  at , 104 

Leeds,  age  of  deposits  in 394 

dultas  iu 480 


INDEX. 


495 


Page. 

Leeds,  osar  in 196-200,381 

Lenticular  deposits,  occurrence  of 32,  382-386 

Levant,  deposits  iu 131, 132 

section  of  osar  in 132 

Lewiston,  deposits  near 56,  57, 201-205, 209, 323 

fossils  at 374,  482 

Liberty,  age  of  deposits  in : . . .  393 

deposits  in 155-158 

LiUy  Bay,  osar  near 135,414 

Limington,  age  of  deposits  in 393 

deposits  in 254-255 

figure  sbo'\Ting  osar  in 258 

Lincoln,  osar  in '. 104,107,114,400 

Lincolu  County,  deposits  in 163-164,168-170 

map  of  ...1 490 

Lindalil,  J.,  cited 270 

Linneus,  osar  in 80 

Litchtield,  deposits  in 186 

Litclifield  Plain,  date  of  deposition  of 393 

features  of 368-369, 452 

Little  Androscoggin  Hirer,  deposits  along 63, 476, 484 

potlioles  in 327-328 

Little  Kiver,  deposits  near 92 

Llvermore,  age  of  deposits  in 394 

erosion  near 66 

osar  in 196, 199,  207,  208,  442 

Livermore  Palls,  deposits  near 484 

Lockes  Mills,  deposits  near 233-234 

figure  showing  deposits  at 12 

figure  showing  stratification  of  sand  at 12 

Lower  Chiputneticook  Lake,  osar  near 70 

Lucia  glacier,  features  of 445 

Lyell,  Charles,  cited 300 

Lynnfield,  'New  Brunswick,  deposits  near 71 

M. 

Machias,  age  of  deposits  in 393 

beach  gravel  near 49,  51 

deposits  iu 85-87,400 

Machias  Lakes,  deposits  near 94, 95 

Machias  Valley,  age  of  deposits  along 393 

deposits  in 88 

Macwahoc,  deposits  in 97, 102, 437-439 

Madison,  delta  in 487 

deposits  in 179-181,  400,  468 

Malaspina  glacier,  features  of 355-358, 420,  421^22, 467 

Manchester,  eskers  in 183, 186 

Manning,  P.  C .,  cited 325 

Mariaville,  deposits  in 118-119 

Marine  clays,  map  of 58 

Marine  deltas,  classification  of 371-373 

elevation  of 482 

features  of 371-376,378 

origin  of 373-374,375-376 

Marine  deposits,  character  of 41-58 

relation  of  till  to  '. 282 

Marion,  deposits  in •. 85, 88 

Marjelen-See,  Switzerland,  character  of 300,  313 

discharge  of 420 

Marr,  J.  E.,  cited 270 

Marsh  Stream,  deposits  along 138, 139, 143 

Martin  Stream,  deposits  along 140-142,143,207-208 

Masardis  Hiver,  deposits  along 362 

Masons  Bay,  deposits  near 91,  94, 112 

Massachusetts,  glacial  conditions  iu 858. 470 


Massives  or  osar  mounds,  features  of 369-371 

Mathew,  G.  F.,  cited 71 

Matinicus  Island,  beach  gravel  iu 47-48,  282-283 

Mattagordus  Stream,  osar  near 99 

Mattakeunk  Stream,  deposits  along 103 

Mattawamkeag  River,  deposits  near 82,  93,  98-99, 103 

deposits  near  branches  of 81,  96 

osar  crossing 437-439 

Maxwell,  D.  F.,  aid  by 95, 100 

cited 73 

Mayfield,  eskers  in 173 

McGee,  W  J,  cited 284 

Mechanic  Falls,  deposits  at 213-214 

Meddybemps,  age  of  deposits  in 393 

osar  near 78, 79 

Medford,  deposits  in 122-125,131,134 

Medford  Ferry,  figure  showing  osar  at 123 

MedomacPond,  deposits  near 162,163 

Medomac  River,  deposits  along 361,  382,  388,  399,  409 

Meduxnikeag  River,  osar  near 75 

Medway,  deposits  in 105, 106, 115, 484 

Menana  Island,  weathered  rocks  on 23 

Mercer,  deposits  in 184-185 

Mesas,  features  of 309-371 

Messalonskee  Pond,  deposits  near 182-183, 184 

Milford,  age  of  deposits  in 393 

Milinoket  Lake,  deposits  near no 

Milo,  deposits  at 135 

Milton,  deposits  in 435^  442 

figure  showing  osar  in 442 

Minot,  deposits  in 214,  381 

Mississippi  Valley,  glacial  conditions  iu 284,  288 

tillin 34- 

Molunkus  Valley,  osar  in 90-97, 437 

Monhegan  Island,  beach  gravel  on 41-17, 281 

weathered  rocks  on 23 

Monmouth,  deposits  iu 190-191 

193-194, 199,  377,  379,  407,  451,  460 

erosion  in 430 

Monroe,  age  of  deposits  in 393 

deposits  in 137^  135 

plates  showing  delta  iu 336,452 

plate  showing  osar  at ' 375 

Mont  Eagle  Plains,  date  of  deposition  of 393 

deposits  on 94 

Montville,  deposits  in 154-157,  322,  331,  430 

erosion  in 429 

map  of  region  near 151 

section  in 152 

Moosehead  Lake,  eskers  near 173 

osar  near 125-131,132-133,400,460 

Moose  Pond,  deposits  near , 148"  171-172 

Mopang  Lake,  deposits  near 95 

Moraines,  comi>osition  of , 270-284 

definition  of. 20-21 

features  of 398 

Morrill,  deposits  in 144-145 

Morrison  Pond,  deposits  near 109, 113 

Moscow,  deposits  in 484, 489 

Mount  Desert  Island,  altitude  of 4OS 

beach  gravels  on 4S 

height  of  ice  sheet  at 295 

Mount  Katahdin,  altitude  of 408 

height  of  ice  sheet  at 295 

osar  near 104-117 

weathering  near 207 


496 


INDEX. 


Page. 

JMount  St.  Elias,  glacial  conditions  on 355-358 

Mount  Vernon,  esker  near 195 

Mousam  Eiver,  deposits  near 256, 259, 262, 263 

Muir  glacier,  features  of 280,  355,  420,  467 

ilunjoy  Hill,  Portland,  deposits  on 215,  283 

fossils  on 53-54 

section  across 32 

Musltingum  Stream,  deposits  near 154-155 

Munson,  condition  of  rock  in 7 

ilusquash  Stream,  osar  near 90-91 

S". 

Naples,  deposits  at 240-241 

Narraguagus  Eiver,  deposits  along 88,101,110,114 

Nevada,  beacli  gravel  in 47 

Newburg,  delta  in 459 

deposits  in 136-137,167 

Kewcastle,  deposits  in 164 

Xewfield,  deposits  iu 256 

plate  showing  osars  in 260 

New  Gloucester,  age  of  deposits  in 393 

delta  at 227-228,456 

deposits  at 227,228,230,234 

New  Hampshire,  glacial  conditions  in 210, 

216,  248,  275,  356,  405,  449,  450,  476,  478 

New  Haven,  Conn.,  pothole  near 330 

New  Limerick,  osar  in 75,  80 

New  Mexico,  glacial  conditions  in 340-343 

Newport,  deposits  in 139-141 

New  Portland,  age  of  deposits  in 394 

deposits  in 188,  356,  419,  474,  479,  484 

New  Vineyard,  esker  near 362 

New  Xork,  glacial  conditions  in 400-401,469-470 

Nickatous  Lake,  deposits  near 95 

Nickatous  Stream,  deposits  near 100 

Niles,W.  H.,  cited 280 

Nohleboro,  deposits  in 163-164 

Norridgewock,  deposits  in 181-lSo 

fossils  in 482 

Nordenskjold,  N.  A.  E.,  cited 269,  270 

North  Acton,  plate  showing  karaes  near 262 

North  Auburn,  age  of  deposits  at 394 

North  Dixmont,  osar  at 310 

Northtield,  deposits  in 90 

North  Mariaville,  deposits  in 118-119 

North  Monmouth,  erosion  near 430 

North  New  Portland,  deposits  near 188,  356,  474 

North  Paris,  deposits  at 442 

North  Scarboro,  age  of  deposits  at 393 

North  Searsmont,  age  of  deposits  at 393 

North  Shapleigh,  delta  iu 459 

North  Waterford,  deposits  near 249-254 

North  Wendham,  deposits  at 484 

North  Woodstock,  deposits  at 219-221, 434, 439, 442 

erosion  near 66 

Norway,  drift  in 476 

raised  beaches  in 300 

0. 

Ohio,  glacial  conditions  in 469 

Old  Stream,  deposits  near 90-92,  94 

Old  Stream  Plains,  date  of  deiwsition  of 393 

Old  Stream  Valley,  age  of  deposits  in 393 

Oldtown,  deposits  iu 124 

Orient,  osar  near 75,80 

Orland,  deposits  in 88,92,113,121-122 


Orneville,  age  of  deposits  in 393 

osar  in 400 

Orono,  deposits  in 124 

Osar-mounds,  features  of 369-371 

Osar  terraces,  features  of 440-448 

Osars,  definitions  of 35,  359 

features  of 361-369,  376-448 

formation  of 330-333,423-425 

stratification  of 423-425 

Ossipee,  N.  H.,  kames  near 449 

Otis,  age  of  deposits  in 393 

delta  in 391-392 

deposits  iu 119,120 

Otisfleld,  deposits  iu 251 

Ouray,  Colo.,  deposits  near 344^345 

Oxbow  Township,  deposits  in 95 

Oxford,  deposits  at 226-227 

drift  near 476 

Oxford  County,  deposits  in. .  206-227,  233-234,  248-262,  318,  478 
map  of 490 


Packard,  A.  3.,  cited 3, 41, 54 

Palermo,  deposits  in 160-162, 167 

kames  in - 147 

Palmyra,  fossils  in 172,482 

Papoose  Pond,  deposits  near 250-252,254 

Paris,  deposits  iu 63,215,222-224,442,484 

pothole  in 327 

section  in 328 

Parkman,  gravel  in 159 

Parlin  Pond,  horsebacks  at 187 

Parsonstield,  deposits  in 256, 257 

plate  showing  deposits  in 332 

Passadumkeag,  osar  in 107 

Passadumkeag  Kiver,  deposits  along 100 

Passagassawawkeag  Pond,  deposits  near 143 

Patten,  osar  in 96,99,425 

Peaked  Mountain,  eskers  near 119 

Peary,  E. E., cited 294,316 

explorations  of 269 

Pembroke,  deposits  in 73,  382 

Penuamaquan  Lake,  deposits  near 73 

Penobscot  Bay,  deposits  near 92, 107, 113, 114, 133,  320,  382 

plate  showing  osar  near 130 

Penobscot  County,  deposits  in 93, 

95-104, 115-117, 119-133, 135-143,  145-147 

map  of 490 

Penobscot  Eiver,  delta  in  valley  of 487 

deposits  along 103-106, 114,  117, 187,  323,  391,  400, 484 

deposits  near  "West  Branch  of 116 

plate  showing  osar  crossing 106 

Penobscot  Valley,  beaches  in 481 

Pequawket  Stream,  deposits  along 258-259 

Perkins  Plantation,  deposits  in 171 

Perley,  S.  F.,  aid  by 95 

Perry.N.H.,  aid  by 327 

Perry,  sandstone  area  in 6 

Peru,  deposits  in 211-213,381,439 

Pikes  Peak  Eauge,  glacial  conditions  in 348-349 

Piscataquis  County,  deposits  in 104-1 17, 

122-126, 134-135, 171, 173 

map  of 490 

Piscataquis  Eiver,  age  of  deposits  along 394 

deposits  along 63, 123-124, 135 

figure  showing  osar  near 123 


IXDEX. 


497 


Pittsfield,  deposits  in 141,148,427 

erosion  at 429 

figure  showing  osar  in 149 

PitlstoD,  deposits  in 171 

Pleasant  Lake,  deposits  near 93 

Pleasant  Eirer,  deposits  along 94-95, 134-135, 227-228, 414 

Plyuioutb    kamesin 145-146 

osar  in 140-142 

Poland,  deposits  in 213-214,226-227 

Poland  Corner,  age  of  deposits  at ?94 

Porter,  deposits  in 256,  257,  259 

plates  showing  deposits  in 448,450 

Portland  deposits  near 215-235, 

242,  283,  323,  361,  380,  388,  434,  439,  442 

figure  showing  landslip  in 232 

fossils  at 53-54,  2g6-291 

section  in 32 

Potholes,  formation  of 324-330 

Pownal,  deposits  in 57,59,202-203,227 

Precipitation  during  glacial  time 292 

Preglacial  land  surface,  character  of 2G5-269 

Prentiss,  deposits  in 99, 102, 126, 437-439 

Presumpscot  River,  deposits  along 242,  484 

formation  of  ridge  along 452 

Prospect,  drift  in 432 

plate  showing  osar  in 332 

P. 

Ragged  Island,  beach  gravel  on 47-48 

Rainfall  during  glacial  time 292 

Raised  beaches,  height  of 481 

Raymond,  osar  at 236, 239 

Readfield,  age  of  deposits  in 393 

deposits  in 189-193 

section  in 32 

Eeadrille,  deposits  near 239 

Rhone  glacier,  features  of 297 

Richmond,  deposits  near 171, 173-174 

Riggs  Landing,  potholes  near 325-327 

Rio  Grande  "Valley,  glacial  conditions  in 343 

Rivers,  character  and  course  of  glacial 5-6,  317-324 

River  terraces,  character  of . . ., 61-63 

origin  of „ 67-68 

Roach  River,  osar  along 134 

Roaring  Fork,  moraines  along 349-350 

Robin  Hoods  Cove,  pc.tholes  on 326 

Rock  Creek,  moraines  along 350 

Rockland,  beach  gravel  near 48-49,  51 

caves  at 308 

glacial  scratches  at 268 

Rocks  of   Maine,   kinds,   condition,    and   mode    of 

weathering  of 6-10 

Rocky  Mountains,  glacial  conditions  in. .  319,  338-355, 398, 405 

Rome,  deposits  in 184 

Royal  River,  deposits  along 202, 214,  228, 237 

Romford,  deposits  in 212,  218, 221-225, 435, 442 

erosion  near 66 

Rumford  Point,  osar  at 248 

Russell,  I.  C,  cited 47, 

273,  296,  316,  317,  347,  355,  357,  397,  420,  467 

quoted 356-357, 445 

Russell  Mountain,  weathering  on 23,  266,  268 

S. 
Sabao  Lake,  deposits  near 95 

Sabattus,  age  of  deposits  at 393 

MON  XXXIV 32 


Sabattus,  deposits  at 285 

Saccarappa,  deposits  near 242 

Saco  River,  age  of  deposits  along 394 

deposits  along  . .  252,  256-257,  258,  394, 461-462,  467,  477, 484 

Sagadahoc  County,  deposits  in 171-174, 186-187 

map  of 490 

St.  Albans,  deposits  in 148, 152 

St.  Croix  Lake,  deposits  near 80 

St.  Croix  River,  deposits  along  and  near 71,  72, 73,  362 

St.  George  River,  deposits  along 147-148, 

154-157,  361,  384,  391,  430 

St.  John  River,  deposits  near 362, 417-418 

St.  Lawrence  River,  glaciation  of 417-418 

Salisbury,  R.  D. ,  cited 266,  284 

Salmon  River  Valley,  glacial  conditions  in 351-355 

moraines  in 352 

Salmon  Stream,  deposits  along 115 

Sam  Ayers  Stream,  osar  along 115-116 

Sands,  character  and  deposition  of 54-58 

Sangerville,  deposits  in 126, 400 

Sandy  River,  age  of  deposits  along 394 

deposits  along 484 

San  Miguel  River  Valley,  deposits  in 343-344 

Saxicava  sand,  occurrence  of 55 

Scarboro,  deposits  in 233, 234, 237 

Schoodic  Lakes,  deposits  near 88 

Schoodic  (Kennebasis)  River,  deposits  near 91 

Schroeppel,  X.  T.,  delta  in 401 

Scotland,  raised  beaches  in 300 

Sea,  former  height  of 481-485 

Sea  level,  determination  of  highest 482 

Searsmont,  deposits  in 147-148, 154-157, 391 

Searsport,  deposits  near 137 

Sea  wall,  section  of 43 

Sebago,  deposits  in 244,246-247 

Sebago  Lake,  deposits  near 63,236-240, 

241-243,251,253,332,484 

plate  showing  osar  near 242 

Sebasticook  River,  deposits  along. . .  156, 159, 168, 171-172, 481 

erosion  by 429 

Sebec  Lake,  deposits  near 135 

Seboois,  deposits  in '. . .  381, 425, 434,  437^39 

Seboois  Lakes,  deposits  near 95-96 

Seboois  River,  age  of  deposits  along 394 

deposits  near 104-106, 116, 425 

weathering  in  valley  of 267 

Sedimentation,  causes  of  discontinuous 395-403 

nature  of .'....       15-18 

Sewall,  J.  W. ,  aid  by 116 

Shaler,  X.  S.,  cited 3, 4,  34,  41,  281, 455 

Shapleigh,  delta  in 459 

Sheepscot  River,  deposits  along  and  near 160,166, 

168-169,  382 

Shelburne,  X.  H.,  deposits  in 275,3513,476,478 

Sherman,  osars  in  and  near 97,  437-439 

section  at 437 

Sherman,  Paul,  cited 3 

Shirley,  deposits  in 125, 173 

Sidney,  age  of  deposits  in 393 

deposits  in ]  82 

Silsby  Plains,  deposits  on 381 

description  of 108-110, 114. 372,  376 

Silverton,  Colo,,  dej^osits  at 341-343 

Sisladobsis  Lake,  deposits  near 94-95 

Sko whegan,  fossils  in 482 

Smyrna,  deposits  in 77^  80-81, 439 


498 


INDEX. 


Page. 

Soil-cap  movement,  transportation  by 10-11 

Solon ,  deposits  in 63, 178 

erosion  near 64 

Souierset  County,  deposits  in ]  48-159, 171-189 

map  of 490 

Sougo  River,  character  of 251 

Soper  Brook,  deposits  near 117 

South  Acton,  osar  near 318 

South  Albion,  deposits  at 165-167,  322 

South  Bridgeton,  dejiosits  near 239 

South  Lincoln,  osar  near 107, 114, 400 

plate  showing  osar  at 106 

South  Paris,  age  of  deposits  at 394 

deposits  near 63, 484 

South  Park,  glacial  conditions  in 349 

South  TwinLake,  deposits  near 284, 285 

Spencer,  J.  W.,  cited 280 

Springtield,  deposits  near 90, 99, 102, 434, 437-439 

plate  showing  deposits  in 104 

section  at 437 

Springs,  transportation  of  soil  by 18-20 

Stacey ville,  deposits  in 115 

Standish,  age  of  deposits  in 393 

deposits  in 243-244,  484 

Stevenson,  David,  cited 14 

Stockton,  plate  showing  osar  in 130 

Stone,  G.H.,  cited 3,4 

Stratton  Brook,  horseback  on T88 

Streams,  character  of  englacial 296-301 

character  of  glacial 291-294 

courses  of  subglacial 297-301,  305-310 

erosion  by 23-24 

sedimentation  by 15-18 

transportation  by 13-20 

Subglacial  streams,  causes  of 305-308 

channels  of 308-310 

direction  of 297-301 

Subterranean  streams,  transpo.tation  of  soil  by 18-20 

Sullivan,  deposits  in 117 

Sumner,  age  of  deposits  in 394 

deposits  in 213-214,215.381,484 

Sunk-haze  Stream,  deposits  along 108 

Sweden,  deposits  in 246, 252, 300 

Switzerland,  glacial  lake  in 300 

T. 

Taylor,  H.E.,  aid  by 88,95 

Telluride,  Colo.,  moraine  near 344 

Temperature  of  ice-sheets 302-304 

Terraces,  features  of 440-448 

Tertiary  beds,  absence  of 27-28 

Thomaston,  gravels  in 147-148 

Thorndike,  age  of  deposits  in 393 

deposits  in '. 143,149,158,435,459 

Till,  character  of 29-30,33-34 

composition  of  lower 277-284 

composition  of  upper 272-277 

distribution  of 31-33 

origin  of 270-272 

Tomah,  deposits  near 284,  320 

Tomah  Stream,  osars  near    76-77, 83 

Topography  of  Maine,  nature  of 5-6 

.    relations  of  glacial  rivers  to 321-323 

TopsBeld,  deposits  in 90-92,94 

Torell,  Q.M., cited 260,271 

Trescott,  csar  in 79 


Page. 

Troy,  deposits  in 141-144, 145-147 

Turner,  age  of  deposits  in 394 

deposits  in 208 

Twentymile  Kiver,  deposits  along 484 

Twitchell,  J.F.,  aid  by 115 

U. 

Umbagog  outlet,  age  of  deposits  near 394 

Uncompahgre  River,  glacial  conditions  in  valley  of.  344-345 

Underground  streams,  transportation  of  soil  by 18-20 

Union,  deposits  near 384 

Union  Kiver,  deltas  in  valley  of 372,374,391-392 

deposits  along  and  near 108-110, 114, 118 

Unity,  age  of  deposits  in 393 

delta  in 435,459,469 

deposits  in.'. 148,149, 150,158 

fossils  in 482 

Upham,  Warren,  cited 32,43,256,284 

Upper  Beddington,  osar  at 101 

Utah,  beach  gravel  in 47 

r. 

Valley  drift,  character  of 58-63,  67-69, 475-489 

composition  of - 485-488 

definition  of 16 

erosion  of 63-67 

origin  of 470-475 

Vanceboro,  osars  in 70-71 

Vassalboro,  deposits  in 169-170,468 

Veazie,  deposits  in 124, 125 

Virginia,  weathering  in 266 

W. 

"Wakefield,  K.H.,  deposits  near 256 

"Waldo,  age  of  deposits  in 393 

deposits  in 138, 143 

Waldoboro,  age  of  deposits  at 393 

deposits  in 162-1 63,  240,  269,  272-274,  283, 

290,  361,  375,  378,  382,  383-385,  387,  399,  409,  419 

plate  showing  moraine  in 262 

Waldo  County,  deposits  in...: 130-131,  135-139,143-163 

map  of , 490 

"Warren,  deposits  in 162 

"Washington,  age  of  deposits  in 393 

Washington  County,  deposits  in 70-104 

map  of 490 

Waterboro,  plate  showing  deposits  in 382 

Waterford,  deposits  in 249-254 

Wat  erville,  delta  in 487 

deposits  in 57, 171, 172 

figure  showing  deposits  in 379 

Wayne,  deposits  in 193-194, 198, 199 

erosion  in 13 

Weathering,  examples  and  effects  of 22-23, 265-269 

methods  of 8-9 

Webster,  deposits  in 99,186, 191,437 

Wellington,  deposits  in 171 

Wells,  Walter,  cited 3,72,78,141,292 

Wells,  osar  in 262-263 

Wesley,  deposits  in 88, 90 

West  Bowdoin,  age  of  deposits  at 393 

plate  showing  deposits  at 186, 378 

West  Erancli  of  Penobscot  Kiver,  deposits  near 106,  116 

Westbrook,  eeker  in 235 

Westcott  Streani,  deposits  near 138 


INDEX. 


499 


Page. 

West  Cumberland,  age  of  deposits  at 393 

"West  Hampden,  deposits  near 130, 136 

"West  Lebanon,  deposits  in  ^ 263 

"West  Mariaville,  massive  near 118 

"West  Minot,  kames  near 214 

"Weston,  osarin 75,82 

"West  Sumner,  deposits  near 213-214 

Whitefield,  deposits  in ._, 168,169 

White  Mountains,  direction  of  ice  flow  in 417 

landslides  in 10 

"Whitney,  J.  D.,  cited 292 

"WhitneyviUe,  deposits  in 90 

Whittlesey,  Charles,  cited 3 

Wilder,  A.  W.,  cited 141 

"Williamsburg,  gravel  near 134 

"Willimantic,  gravel  in 135 

"Wilton,  eskers  in 205, 366 

"Wind,  drift  forms  due  to 24^25 

transportation  of  soil  by 11-13 

Windham,  deposits  in 236-238, 484 

AVindsor,  age  of  deposits  in 393 

deposits  in 164, 168-170 

plate  showing  deposits  in 170,454 


"Winn,  deposits  in 103-104 

Winslo w,  deposits  in 168-170 

Winslows  Mills,  deposits  near 163, 240, 272-274, 382, 399 

plate  showing  moraine  at 262 

Wisconsin,  moraines  in 398 

weathering  in 266 

Winterport,  deposits  in 130 

Winthrop,  deposits  in 189,193 

fossils  in 482 

Wood,  William,  cited 287 

Woodstock,  deposits  in 215, 219-221, 434, 435, 439, 442 

erosion  in 66 

plate  showing  osar  in 220,442 

section  across  osar  in 442 

Wright,  G.  F.,  cited 3,  280,  296,  355,  420,  424,  467 


Yarmouth,  deposits  in 57, 203, 215, 230 

York  County,  Me.,  delta  plains  in 374,  375, 387 

deposits  in 255-263,  318, 478 

map  of 490 

York  County,  New  Brunswick,  deposits  in 70-71 


A.DVERTISE1VIENT. 

[Monograph  XXXIV.] 


The  statute  approved  March  3,  1879,  establishing  the  United  States  Geological  Survey,  contains 
the  following  provisions : 

"The  publications  of  the  Geological  Survey  shall  consist  of  the  annual  report  of  operations,  geo- 
logical and  economic  maps  illustrating  the  resources  and  classification  of  the  lauds,  and  reports  upon 
general  and  economic  geology  and  paleontology.  The  annual  report  of  operations  of  the  Geoloo-ical 
Survey  shall  accompany  the  annual  report  of  the  Secretary  of  the  Interior.  All  special  memoirs^and 
reports  of  said  Survey  shall  be  issued  in  uniform  quarto  series  if  deemed  necessary  by  the  Director,  but 
otherwise  iu  ordinary  octavos.  Three  thousand  copies  of  each  shall  be  published  for  scientific  exchanges 
and  for  sale  at  the  price  of  publication ;  and  all  literary  aud  cartographic  materials  received  in  exchange 
shall  be  the  property  of  the  United  States  and  form  a  part  of  the  library  of  the  organization:  And  the 
money  resulting  from  the  sale  of  such  publioatious  shall  be  covered  into  the  Treasury  of  the  United 
States." 

Except  in  those  cases  in  which  an  extra  number  of  any  special  memoir  or  report  has  been  sup- 
plied to  the  Survey  by  special  resolution  of  Congress  or  has  been  ordered  by  the  Secretary  of  the 
Interior,  this  office  has  no  copies  for  gratuitous  distribution. 

ANNUAL  REPORTS. 

I.  First  Annual  Report  of  the  United  States  Geological  Survey,  by  Clarenie  King.  1880.  8°.  79 
pp.     1  map. — A  preliminary  report  describing  plan  of  organization  and  publications. 

II.  Second  Annual  Report  of  the  United  States  Geological  Survey,  1880-'81,  by  J.  W.  Powell 

1882.  8°.    Iv,  588  pp.     62  pi.     1  map. 

III.  Third  Annual  Report  of  the  United  States  Geological  Survey,  1881-'82,  by  J.  W.  Powell 

1883.  8°.     xviii,  564  pp.     67  pi.  and  maps. 

IV.  Fourth  Annual  Report  of  the  United  States  Geological  Survey,  1882-'83,  by  J.  W.  Powell. 

1884.  8°.     xxxii,  473  pp.     85  pi.  aud  maps. 

V.  Fifth  Annual  Report  of  the  United  States  Geological  Survey,  1883-'84,  by  J.  AV.  Powell. 

1885.  8°.     xxxvi,  469  pp.     58  pi.  and  maps. 

VI.  Sixth  Annual  Report  of  the  United  States  Geological  Survey,  1884-'85,  by  J.  W.  Powell. 
1885.     8°.     xsix,  570  pp.     65  pi.  and  maps. 

VII.  Seventh  Annual  Report  of  the  United  States  Geological  Survey,  1885-'86,  by  .J.  W.  Powell. 

1888.  8°.     XX,  656  jJii.     71  pi.  and  maps. 

VIII.  Eighth  Annual  Report  of  the  United  States  Geological  Survey,  1886-'87,  by  J.  W.  Powell 

1889.  8°.     2pt.     xis,  474,  xii  pp.,  53  pi.  and  maps;  1  prel.  leaf,  475-1063  pp.,  54-76  pi.  and  maps. 

IX.  Ninth  Annual  Report  of  the  United  States  Geological  Survey,  1887-'88,  bv  J.  W.  Powell. 

1889.  8'^.     xiii,  717  pp.     88  pi.  and  maps. 

X.  Tenth  Annual  Report  of  the  United  States  Geological  Survey,  1888-'89,  by  J.  W.  Powell. 

1890.  8°.     2  pt.     XV,  774  pp.,  98  pi.  and  maps ;  viii,  123  pp. 

XI.  Eleventh  Annual  Report  of  the  United  States  Geological  Survey,  1889-'90,  by  J.  W.  Powell. 

1891.  8^.     2pt.     XV,  757  pp.,  66  pi.  and  maps;  ix,  351pp.,  30  pi.  and  maps. 

XII.  Twelfth  Annual  Report  of  the  United  States  Geological  Survey,  1890-=91,  by  J.  W.  Powell. 
1891.     8°.    2  pt.,  xiii,  675  pp.,  53  pi.  and  maps ;  xviii,  576  pp.,  146  pi.  and  maps. 

XIII.  Thirteenth  Annual  Report  of  the  United  States  Geological  Survey,  1891-'92,  by  J.  W. 
Powell.  1893.  8°.  3  pt.  vii,  240  pp.,  2  maps;  x,  372  pp.,  105  pi.  and  maps;  x'i,  486  pp.,  77  pi.  and 
maps. 

XIV.  Fourteenth  Annual  Report  of  the  United  States  Geological  Survev,  1892-'93,  by  J.  W. 
Powell.    1893.     8^.     2  pt.     vi,  321  pp.,  1  pi. ;  xx,  597  pp.,  74  jjl.  and  maps. 

XV.  Fifteenth  Annual  Report  of  the  United  States  Geological  Survey,  1893-'94,  by  J.  W.  Powell. 
1895.     8°.     xiv,  755  pp.,  48  pi.  and  maps. 

XVI.  Sixteenth  Annual  Report  of  the  United  States  Geological  Survey,  1894-'95,  Charles  D. 
Walcott,  Director.  1895.  (Part  I,  1896.)  8°.  4  pt.  xxii,  910  pp.,  117  pi.  and  maps;  xix,  598  pp..  43 
pi.  and  maps;  xv,  646  pp.,  23  pi. ;  xix,  735  pp.,  6  pi. 

XA^II.  Seventeenth  Annual  Report  of  the  United  States  Geological  Survey,  1895-'96,  Charles 
D.  Walcott,  Director.  1896.  8'^.  3  pt.  in  4  vol.  xxii,  1076  pp.,  67  pi.  and  maps ;  xxv,  864  pp.,  113  pi. 
and  maps;  xxiii,  542  pp.,  8  pi.  and  maps;  iii, 543-1058  pp.,  9-13  pi. 

XVIII.  Eighteenth  Annual  Report  of  the  United  States  Geological  Survey,  1896-'97,  Charles  D. 
Walcott,  Director.     1897.    (Parts  II  and  III,  1898.)     8°.    opt.  in  6  vol.     1-440  pp.,  4  pi.  and  maps;  i-v, 


II  ADVERTISEMENT. 

1-653  pp..  105  pi.  and  maps;  i-v,  1-861  pp.,  118  pi.  audiiiaps;  i-x,  1-756  pp.,  102  pi.  and  maps;  i-sii, 
1-642  pp.,  1  pi. ;  643-1400  pp. 

XIX.  Niaetoenth  Annual  Report  of  the  United  States  Geological  Survey,  1897-'98,  Charles  D. 
Walcott,  Director.     1898.     8°.     6  pt.  in  7  a-oI. 

ilOXOGRAPHS. 

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III.  Geology  of  the  Comstock  Lode  and  the  Washoe  District,  with  Atlas,  by  George  F.  Becker. 
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V.  The  Copper-Bearing  Rocks  of  Lake  Superior,  by  Roland  Duer  Irving.  1883.  4'^.  xvi,  464 
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VI.  Contributions  to  the  KnoTvledge  of  the  Older  Mesozoic  Flora  of  Virginia,  by  AVilliam  Morris 
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VII.  Silver-Lead  Deposits  of  Eureka,  Nevada,  by  Joseph  Storv  Curtis.  1884.  4^.  xiii,  200  pp. 
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X.  Dinocerata.  A  Monograph  of  an  Extinct  Order  of  Gigantic  JIammals,  by  Othniel  Charles 
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XI.  Geological  History  of  Lake  Lahontan,  a  Quaternary  Lake  of  Northwestern  Nevada,  by 
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XII.  Geology  and  Mining  Industry  of  Leadville,  Colorado,  with  Atlas,  by  Samuel  Franklin 
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XIII.  Geology  ofthe  Quicksilver  Deposits  ofthe  Pacific  Slope,  with  Atlas,  bv  George  F.  Becker. 
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by  Robert  P.  Whitfield.     1891.     4°.     402  pp.     50  pi.     Price  $1.00. 

XIX.  The  Peuokee  Iron-Bearing  Series  of  Northern  Wisconsin  and  ilichigan,  by  Roland  D. 
Irving  and  C.  R.  Van  Hise.     1892.     4°.     six,  534  pp.     Price  $1.70. 

"xx.  Geology  of  the  Eureka  District,  Nevada,  with  an  Atlas,  by  Arnold  Hague.  1892.  4°.  xvii, 
419  pp.     8  pi.     Price  $5.25. 

XXI.  The  Tertiary  Rhynchophorous  Coleoptera  of  the  United  States,  by  Samuel  Hubbard  Scud- 
der.     1893.     4°.     xi,  206  pp.     12  pi.     Price  90  cents. 

XXII.  A  Manual  of  Topographic  Methods,  by  Henry  Gannett,  Chief  Topographer.  1893.  4°, 
xiv.  300  pp.     18  pi.    Price  $1.00. 

XXIII.  Geology  ofthe  Green  Mountains  in  Massachusetts,  by  Raphael  Pumpellv,  T.  Nelson  Dale, 
and  J.  E.  Wolft'.     1894.     4<=.     xiv,  206  pp.     23  pi.     Price  $1.30. 

XXIV.  Mollusca  and  Crustacea  ofthe  Miocene  Formations  of  New  Jersey,  by  Robert  Parr  Whit- 
field.    1894.     4°.     193  pp.     24  pi.     Price  90  cents. 

XXV.  TheGlacialLakeAgassiz,  by  Warren  Upham.   1895.   4'^.  xxiv,  658  pp.   38  pi.   Price  $1.70. 

XXVI.  Flora  6f  the  Amboy  Clavs,  by  John  Strong  Newberry;  a  Posthumous  Work,  edited  by 
Arthur  Hollick.     1895.    4-.     260  pp.     58  pi.     Price  $1.00. 

X  XVII.  Geology  of  the  Denver  Basin  in  Colorado,  by  Samuel  Franklin  Emmons,  Whitman  Cross, 
and  George  HomansEldridge.     1896.     4°.     556  pp.     31  pi.     Price  $1.50. 

XXVIII.  The  Marquette  Iron-Bearing  District  of  Michigan,  with  Atlas,  by  C.  R.  Van  Hise  and 
W.  S.  Bayley,  including  a  Chapter  on  the  Republic  Trough,  by  H.  L.  Smyth.  1895.  4°.  608  pp.  35 
pi.  and  atlas  of  39  sheets  folio.     Price  $5.75. 

XXIX.  Geology  of  Old  Hampshire  County,  Massachusetts,  comprising  Franklin,  Hampshire,  and 
Hampden  Counties,  by  Benjamin  Kendall  Emerson.     1898.     4°.     xxi,  790  pp.     35  pi.     Price  $1.90. 

XXX.  Fossil  Medus:e,  by  Charles  Doolittle  Walcott.     1898.     4^.     ix,201pp.     47  pi.     Price  $1.50. 

XXXI.  Geology  of  the  Aspen  Mining  District,  Colorado,  with  Atlas,  by  Josiah  Edward  Spurr. 
1898.     4-.     XXXV,  260  pp.     43  pi.  and  atlas  of  30  sheets  folio.     Price  $3.60. 

XXXtll.  Geology  of  the  Yellowstone  National  Park,  Part  II,  Descriptive  Geology,  Petrography, 
and  Paleontology,  by  Arnold  Hague,  J.  P.  Iddings,  W.  Harvey  Weed.  Charles  D.  Walcott,  G.  H.  Girty, 
T.  W.  Stanton,  and  F.  H.  Knowlton.     1899.     4-.     xvii,  893  pp.     121  pi.     Price . 

XXXIII.  Geology  of  the  Narragausett  Basin,  by  N.  S.  Shaler,  J.  B.  Woodworth,  and  August  F. 
Foerste.     1899.     4^.     xx,  402  pp.     31  pi.     Price . 


ADVERTISEMENT.  Ill 

XXXIY.  The  Glacial  Gravels  of  Maine  and  their  Associated  Deposits,  by  George  H.  Stone.    1899. 
xiii,  499  pp.     52  pi.     Price . 

XXXV.  The  Later  Extinct  Floras  of  North  America,  by  John  Strong  Newberry;  edited  by 
Arthur  HoUick.     1898.     4=.     xviii,  295  pp.     68  pi.     Price  $1.25. 

In  preparaiion: 

XXXVI.  The  Crystal  Falls  Iron-Bearing  District  of  Michigan,  by  J.  Morgan  Clements  and 
Henry  Lloyd  Smyth ;  with  a  Chapter  on  the  Sturgeon  River  Tongue,  by  William  Shirley  Bayley. 

'  XXXVII.  Flora  of  the  Lower  Coal  Measures  of  Missouri,  by  David  White. 
XXXVIII.  The  Illinois  Glacial  Lobe,  by  Frank  Leverett. 
— Flora  of  the  Laramie  and  Allied  Formations,  by  Frank  Hall  Knowlton. 

BULLETINS. 

1.  On  Hypersthene-Andesite  and  on  Triclinic  Pyroxene  in  Augitio  Rocks,  by  Whitman  Cross, 
with  a  Geological  Sketch  of  Bufl'alo  Peaks,  Colorado,  by  S.  F.  Emmons.  1883.  8'^.  42  pp.  2  pi, 
Price  10  cents. 

2.  Gold  and  Silver  Conversion  Tables,  giving  the  Coining  Values  of  Troy  Ounces  of  Fine  Metal, 
etc.,  computed  by  Albert  Williams,  jr.     1883.    8'^.     8  pp.     Price  5  cents. 

3.  On  the  Fossil  Faunas  of  the  Ujiper  Devonian,  along  the  Meridian  of  76°  30',  from  Tompkins 
County,  N.  Y.,  to  Bradford  County,  Pa.,  by  Henry  S.  Williams.     1884.     8".     36  pp.     Price  5  cents. 

4.  On  Mesozoic  Fossils,  liy  Charles  A.  White.     1884.     8-\     36  pp.     9  pi.     Price  5  cents. 

5.  A  Dictionary  of  Altitudes  in  the  United  States,  compiled  by  Henry  Gannett.  1884.  8°.  325 
pp.     Price  20  cents. 

6.  Elevations  in  the  Dominion  of  Canada,  by  J.  AV.  Spencer.     1884.     8°.     43  pp.     Price  5  cents. 

7.  Mapoteoa  Geologica  Americana.  A  Catalogue  of  Geological  Maps  of  America  (North  and 
South),  1752-1881,  in  Geographic  and  Chronologic  Order,  by  Jules  Marcou  and  John  Belknap  Maroon. 

1884.  8^.     184  pp.     Price  10  cents. 

8.  On  Secondary  Enlargements  of  Mineral  Fragments  in  Certain  Rooks,  by  R.  D.  Irving  and 
C.  R.  Van  Hise.     1884.     8°.     56  pp.      6  pi.     Price  10  cents. 

9.  A  Report  of  Work  done  in  the  Washington  Laboratory  during  the  Fiscal  Year  1883-'84.  F.  W. 
Clarke,  Chief  Chemist ;  T.  M.  Chatard,  Assistant  Chemist.     1884.     8°.     40  pp.     Price  5  cents. 

10.  On  the  Cambrian  Faunas  of  North  America.  Preliminary  Studies,  by  Charles  Doolittle 
Walcott.     1884.     8°.     74  pp.     10  pi.     Price  5  cents. 

It.  On  the  Quaternary  and  Recent  Mollusca  of  the  Great  Basin;  with  Description  of  New 
Forms,  by  R.  Ellsworth  Call.  Introduced  bv  a  Sketch  of  the  Quaternary  Lakes  of  the  Great  Basin, 
by  G.  K.  Gilbert.     1884.     8'=.     66  pp.     6  pi.  '  Price  5  cents. 

12.  A  Crystallographic  Study  of  the  Thiuolite  of  Lake  Lahontan,  by  Edward  S.  Dana.  1884.  8°. 
34  pp.     3  pi.     Price  5  cents. 

13.  Boundaries  of  the  United  States  and  of  the  Several  States  and  Territories,  with  a  Historical 
Sketch  of  the  Territorial  Changes,  by  Henry  Gannett.     1885.     8°.     135  pp.     Price  10  cents. 

14.  The  Electrical  and  Magnetic  Properties  of  the  Iron- Carburets,  by  Carl  Barus  and  Vincent 
Strouhal.     1885.     8°.    238  pp.     Price  15  cents. 

15.  On  the  Mesozoic  and  Cenozoic  Paleontology  of  California,  by  Charles  A.  White.  1885.  8°. 
33i3p.     Price  5  cents. 

16.  On  the  Higher  DevonianFaunasofOntarioCounty,  New  Yoi'k,  by  John  M.  Clarke.  1885.  8°. 
86  pp.     3  pi.     Price  5  cents. 

17.  On  the  Development  of  Crystallization  in  the  Igneous  Rocks  of  Washoe,  Nevada,  with  Notes 
on  the  Geology  of  the  District,  by  Arnold  Hague  and  Joseph  P.  Iddings.  1885.  »■>.  44  pp.  Price  5 
cents. 

18.  On  Marine  Eocene,  Fresh-Water  Miocene,  and  other  Fossil  Mollusca  of  Western  North 
America,  by  Charles  A.  White.     1885.    S'^.     26  pp.     3  pi.     Price  5  cents. 

19.  Notes  on  the  Sti-atigraphy  of  California,  by  George  F.Becker.   1885.   8^.   28  pp.   Price  5  cents. 

20.  Contributions  to  the  Mineralogy  of  the  Rocky  Mountains,  by  Whitman  Cross  and  W.  F.  Hille- 
brand.     1885.     8^.     114  pp.     1  pi.     Price' 10  cents. 

21.  The  Lignites  of  the  Great  Sioux  Reservation;  a  Report  on  the  Region  between  the  Grand 
and  Moreau  Rivers,  Dakota,  by  Bailey  Willis.     1885.     8°.     16  pp.     5  pi.     Price  5  cents. 

22.  On  New  Cretaceous  Fossils  from  California,  by  Charles  A.  White.  1885.  8°.  25  pp.  5  pi. 
Price  5  cents. 

23.  Observations  on  the  Junction  between  the  Eastern  Sandstone  and  the  Keweenaw  Series  on 
Keweenaw  Point,  Lake  Superior,  by  R.  D.  Irving  and  T.  C.  Chamberlin.  1885.  8*^.  124  pp.  17  pi. 
Price  15  cents. 

24.  List  of  Marine  Mollusca,  comprising  the  Quaternary  Fossils  and  Recent  Forms  from  American 
Localities  between  Cape  Hatteras  and  Cape  Roque,  including  the  Bermudas,  by  William  Healey  Dall. 

1885.  8"^.     336  pp.     Price  25  cents. 

25.  The  Present  Technical  Condition  of  the  Steel  Industry  of  the  United  States,  by  Phineas 
Barnes.     1885.     8°.     85  pp.     Price  10  cents. 

26.  Copper  Smelting,  by  Henry  M.  Howe.     1885.     8°.     107  pp.     Price  10  cents. 

27.  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal  Year 
1884-'85.     1886.     8°.     80  pp.     Price  10  cents. 

28.  The  Gabbros  and  Associated  Hornblende  Rocks  occurring  in  the  Neighborhood  of  Baltimore, 
Maryland,  by  George  Huntington  Williams.     1886.     8°.     78  pp.     4  pi.    Price  10  cents. 


IV  ADVERTISEMENT. 

29.  OatheFresli-Waterlnvertebratesof  the  NorthAmerican  Jurassic,  byCliarles  A.  White.  1886. 
8^.    41  pp.     4  pi.     Price  5  cents. 

30.  Second  Contribution  to  the  Studies  on  the  Cambrian  Faunas  of  North  America,  by  Charles 
Doolittle  Walcott.     1886.     S^.     369  pp.     33  pi.     Price  25  cents. 

31.  Systematic  Eevie-sv  of  our  Present  Knowledge  of  Fossil  Insects,  including  Myriapods  and 
Arachnids,  by  Samuel  Hubbard  Scudder.     1886.     8°.     128  pp.     Price  15  cents. 

32.  Lists  and  Analyses  of  the  Mineral  Springs  of  the  United  States ;  a  Preliminary  Study,  by 
Albert  C.  Peale.     1886.     8°.     235  pp.     Price  20  cents. 

33.  Notes  on  the  Geology  of  Northern  California,  by  J.  S.Diller.     1886.    8°.    23  pp.    Price  5  cents. 

34.  On  the  Relation  of  the  Laramie  Molluscau  Fauna  to  that  of  the  Succeeding  Fresh-Water  Eocene 
and  Other  Groups,  by  Charles  A.  White.     1886.     8^=.     54  pp.     5  pi.     Price  10  cents. 

35.  Physical  Properties  of  the  Iron-Carburets,  by  Carl  Barus  and  Vincent  Strouhal.  1886.  8°. 
62  pp.     Price  10  cents. 

36.  Subsidenceof FineSolidParticlesinLiquidSjbyCarlBarus.     1886.    8*^.    58pp.    Price lOcents. 

37.  Types  of  the  Laramie  Flora,  by  Lester  F.AVard.     1887.     8'^.     354  pp.     57  pi.     Price  25  cents. 

38.  PeridotiteofEUiottCounty,  Kentucky,  by  J.  S.Diller.     1887.     8-^.    31pp.    Ipl.    PriceScents. 

39.  The  Upper  Beaches  and  Deltas  of  the  Glacial  Lake  Agassiz,  by  Warren  Upham.  1887.  8°. 
84  pp.     1  pi.     Price  10  cents. 

40.  Changes  in  Ri-^-er  Courses  in  Washington  Territory  due  to  Glaciation,  by  Bailey  Willis.  1887. 
8°.     10  pp.     4  pi.     Price  5  cents. 

41.  On  the  Fossi',  Faunas  of  the  Upper  Devonian — the  Genesee  Section,  Neiv  York,  by  Henry  S. 
Williams.     1887.     8'='.     121  pp.     4  pi.     Price  15  cents. 

42.  Reportof  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal  Year 
lS85-'86.     F.  W.  Clarke,  Chief  Chemist.     1887.     8^.     152  pp.     1  pi.     Price  15  cents. 

43.  Tertiary  and  Cretaceous  Strata  of  the  Tuscaloosa,  Tomhigbee,  and  Alabama  Rivers,  by  Eugene 
A.  Smith  and  Lawrence  C.  Johnson.     1887.     8'^.     189  pp.     21  pi.     Price  15  cents. 

44.  Bibliography  of  North  American  Geology  for  1886,  by  Nelson  H.  Darton.     1887.     8^.     35  pp. 

45.  The  Present  Condition  of  Knowledge  of  the  Geology  of  Texas,  by  Robert  T.  Hill.  1887.  8^. 
94  pp.     Price  10  cents. 

46.  Nature  and  Origin  of  Deposits  of  Phosphate  of  Lime,  by  R.  A.  F.  Penrose,  jr.,  with  an  Intro- 
duction by  N.  S.  Shaler.     1888.     8°.     143  pp.     Price  15  cents. 

47.  Analyses  of  Waters  of  the  Y'ellowstone  National  Park,  with  an  Account  of  the  Methods  of 
Analysis  emplo'yed,  by  Frank  Austin  Gooch  and  James  Edward  'Whitiield.  1888.  8°.  84  pp.  Price 
10  cents. 

48.  On  the  Form  and  Position  of  the  Sea  Level,  by  Robert  Simpson  Woodward.  1888.  8"^.  88 
pp.     Price  10  cents. 

49.  Latitudes  and  Longitudes  of  Certain  Points  in  Missouri,  Kansas,  and  New  Mexico,  by  Robert 
Simpson  Woodward.     1889.     8^.     133  pp.     Price  15  cents. 

50.  Formulas  and  Tables  to  Facilitate  the  Construction  and  Use  of  Maps,  by  Robert  Simpson 
Woodward.     1889.     8^.     124  pp.     Price  15  cents. 

51.  On  Invertebrate  Fossils  from  the  Paciiic  Coast,  by  Charles  Abiathar  White.  1889.  8°.  102 
pp.     14  pi.     Price  15  cents. 

52.  Subaerial  Decay  of  Rocks  and  Origin  of  the  Red  Color  of  Certain  Formations,  by  Israel 
Cook  Russell.     1889.    8^.    65  pp.    5  pi.    Price  10  cents. 

53.  The  Geology  of  Nantucket,  by  Nathaniel  Southgate  Shaler.  1889.  8-^.  55  pp.  10  pi.  Price 
10  cents. 

54.  On  the  Thermo-Electric  Measurement  of  High  Temperatures,  by  Carl  Barus.  1889.  8°. 
313  pp.,  incl.  1  pi.     11  111.     Price  25  cents. 

55.  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal 
Year  1886-'87.    Frank  Wigglesworth  Clarke,  Chief  Chemist.    1889.    8'^.    96  pp.     Price  10  cents. 

56.  Fossil  Wood  and  Lignite  of  the  Potomac  Formation,  by  Frank  Hall  Knowlton.  1889.  8'='. 
72  pp.     7  pi.     Price  10  cents. 

57.  A  Geological  Reconnoissance  in  Southwestern  Kansas,  by  Robert  Hay.  1890.  8^.  49  pp. 
2  pi.     Price  5  cents. 

58.  The  Glacial  Boundary  in  Western  Pennsylvania,  Ohio,  Kentucky,  Indiana,  and  Illinois,  by 
George  Frederick  Wright,  witli  an  Introduction  by  Thomas  Chrowder  Chamberlin.  1890.  8-^.  112 
pp.,  incl.  1  pi.     8  pi.     Price  15  cents. 

59.  The  Gabbros  and  Associated  Rocks  in  Delaware,  by  Frederick  D.  Chester.  1890.  S^.  45 
pp.     1  pi.     Price  10  cents. 

60.  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal 
Year  1887-'88.     F.  W.  Clarke,  Cliief  Chemist.     1890.     8^^.     174  pp.     Price  15  cents. 

61.  Contributions  to  the  Mineralogy  of  the  Paciiic  Coast,  by  William  Harlow  Melville  and  Wal- 
demar  Lindgren.     1890.    8^.     40  pp.     3  pi.     Price  5  cents. 

62.  The  Greenstone  Schist  Areas  of  the  Menominee  and  Marquette.  Regions  of  Michigan,  a  Con- 
tribution to  the  Subject  of  Dynamic  Metamorphism  in  Eruptive  Rocks,  by  George  Huntington  Williams, 
with  an  Introduction  by  Roland  Duer  Irving.     1890.     8^.     241  pp.     16  pi.     Price  30  cents. 

63.  A  Bibliography  of  Paleozoic  Crustacea  from  1698  to  1889,  including  a  List  of  North  Amer- 
ican Species  and  a  Systematic  Arrangement  of  Genera,  by  Anthony  W.  Vogdes.     1890.     8^.     177  pp. 

64.  A  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal 
Year  1888-'89.     F.  W.  Clarke,  Chief  Chemist.     1890.     8-^.     60  pp.     Price  10  cents. 


ADVERTISEMENT.  V 

65.  Stratigraphy  of  the  Bitumiuous  Coal  Field  of  Pennsylvania,  Ohio,  and  West  Viro-inia,  by 
Israel  C.  White.     1891.     8^.     212  pp.     11  pi.     Price  20  cents. 

66.  On  a  Gronp  of  A''olcanic  Rooks  from  the  Tewan  Mountains,  New  Mexico,  and  on  the  Occur- 
rence of  Primary  Quartz  in  Certain  Basalts,  by  Joseph  Passon  Iddings.  1890.  8°.  34  pp.  Price  5 
cents. 

67.  The  Relations  of  the  Traps  of  the  Newark  System  in  the  New  Jersey  Region,  by  Nelson 
Horatio  Darton.     1890.     8'^.     82  pp.     Price  10  cents. 

68.  Earthquakes  in  California  in  1889,  by  James  Edward  Keeler.  1890.  8^.  25  pp.  Price  5 
cents. 

69.  A  Classed  and  Annotated  Biography  of  Fossil  Insects,  by  Samuel  Howard  Scudder.  1890. 
8'=.     101pp.     Price  15  cents. 

70.  A  Report  on  Astronomical  Work  of  1889  and  1890,  by  Robert  Simpson  Woodward.  1890.  8'=. 
79  pp.     Price  10  cents. 

71.  Index  to  the  Known  Fossil  Insects  of  the  AVorld,  including  Myriapods  and  Arachnids,  by 
Samuel  Hubbard  Scudder.     1891.     8°.     744  pp.     Price  50  cents. 

72.  Altitudes  between  Lake  Superior  and  the  Rocky  Mountains,  by  Warren  Upham.  1891.  8''. 
229  pp.     Price  20  cents. 

73.  The  Viscosity  of  Solids,  by  Carl  Barns.     1891.     8^.     xii,  139  pp.     6  pi.     Price  15  cents. 

74.  The  Minerals  of  North  Carolina,  by  Frederick  Augustus  Genth.  1891.  8°.  119  pp.  Price 
15  cents. 

75.  Record  of  North  American  Geology  for  1887  to  1889,  inclusive,  by  Nelson  Horatio  Darton. 
1891.     8°.     173  pp.     Price  15  cents. 

I  76.  A  Dictionary  of  Altitudes  in  the  United  States  (Second  Edition),  compiled  by  Henry  Gannett, 

'  Chief  Topographer.     1891.     8°.     393  pp.     Price  25  cents. 

i  77.  The  Texan  Permian  and  its  Mesozoic  Types  of  Fossils,  by  Charles  A.  White.     1891.     8°.     51 

I  pp.     4  pi.     Price  10  cents. 

78.  A  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal 
Year  1889-'90.     F.  W.  Clarke,  Chief  Chemist.     1891.     8".     131  pp.     Price  15  cents. 

79.  A  Late  Volcanic  Eruption  in  Northern  California  and  its  Peculiar  Lava,  by  J.  S.  Diller. 

80.  Correlation  Papers — Devonian  and  Carboniferous,  by  Henry  Shaler  Williams.  1891.  8°. 
279  pp.     Price  20  cents. 

81.  Correlation  Papers — Cambrian,  by  Charles  Doolittle  AValcott.  1891.  8°.  547  pp.  3  pi. 
Price  25  cents. 

82.  Correlation  Papers— Cretaceous,  by  Charles  A.  White.  1891.  8°.  273  pp.  3  pi.  Price  20 
cents. 

83.  Correlation  Papers— Eocene,  by  William  Bullock  Clark.  1891.  8^=.  173  pp.  2  pi.  Price 
15  cents. 

84.  Correlation  Papers— Neocene,  by  W.  H.  Dall  and  G.  D.  Harris.  1892.  8°.  349  pp.  3  pi. 
Price  25  cents. 

85.  Correlation  Papers — The  Newark  System,  by  Israel  Cook  Russell.  1892.  8^.  344  pp.  13  pi. 
Price  25  cents. 

86.  Correlation  Papers — Archean  and  Algonkiau,  by  C.  R.  Van  Hise.  1892.  8*^.  549  pp.  12  pi. 
Price  25  cents. 

87.  A  Synopsis  of  American  Fossil.  Brachiopoda,  including  Bibliography  and  Synonymy,  by 
Charles  Schuchert.     1897.     8°.     464  pp.     Price  30  cents. 

88.  The  Cretaceous  Foraminifera  of  New  Jersey,  by  Rufus  Mather  Bagg,  Jr.  1898.  8°.  89  pp. 
6  pi.     Price  10  cents. 

89.  Some  Lava  Flows  of  the  Western  Slope  of  the  Sierra  Nevada,  California,  by  F.  Leslie 
Ransome.     1898.     8°.     74  pp.     11  pi.     Price  15  cents. 

90.  A  Report  of  Work  done  in  the  Division  of  Chemistry  and  Physics,  mainly  during  the  Fiscal 
Year  1890-'91.     F.  AV.  Clarke,  Chief  Chemist.     1892.     8°.     77  pp.     Price  10  cents. 

91.  Record  of  North  American  Geology  for  1890,  by  Nelson  Horatio  Darton.  1891.  8^.  88  pp. 
Price  10  cents. 

92.  The  Compressibility  of  Liquids,  by  Carl  Barns.     1892.     8°.     96  pp.     29  pi.     Price  10  cents. 

93.  Some  Insects  of  Special  Interest  from  Florissant,  Colorado,  and  Other  Points  in  the  Tertiaries 
of  Colorado  and  Utah,  by  Samuel  Hubbard  Scudder.     1892.     8^^.     35  pp.     3  pi.     Price  5  cents. 

94.  The  Mechanism  of  Solid  Viscosity,  by  Carl  Barus.     1892.     8^.     138  pp.     Price  15  cents. 

95.  Earthquakes  in  California  in  1890  and  1891,  by  Edward  Singleton  Holden.  1892.  8°.  31pp. 
Price  5  cents. 

96.  The  Volume  Thermodynamics  of  Liquids,  by  Carl  Barns.     1892.     8^^.     100  jjp.     Price  10  cents. 

97.  The  Mesozoic  Echinodermata  of  the  United  States,  by  W.B.Clark.  1893.  S°.  207  pp.  50pl. 
Price  20  cents. 

98.  Flora  of  the  Outlying  Carboniferous  Basins  of  Southwestern  Missouri,  by  David  AVhite. 
1893.     8'-'.     139  pp.     5  pi.     Price  15  cents. 

99.  Record  of  North  American  Geology  for  1891,  by  Nelson  Horatio  Darton.  1892.  8^.  73  pp. 
Price  10  cents. 

100.  Bibliography  and  Index  of  the  Pulili cations  of  the  U.  S.  Geological  Survey,  1879-1892,  by 
Philip  C'reveling  Warman.     1893.     8^.     495  pj).     Price  25  cents. 

101.  Insect  Fauna  of  the  Rhode  Island  Coal  Field,  by  Samuel  Hubbard  Scudder.  1893.  8^. 
27  pp.     2  pi.     Price  5  cents. 

102.  A  Catalogue  and  Bibliography  of  North  American  Mesozoic  luvertebrata,  Ijy  Cornelius 
Breckinridge  Boyle.     1892.     8°.     315  pp.     Price  25  cents. 


VI  ADVERTISEMENT. 

103.  High  Temperature  Work  in  Igneous  Fusion  and  Eliullition,  chiefly  iu  Relation  to  Pressure, 
hy  Carl  Barns.     1893.     8°.     57  pp.     9  pi.     Price  10  cents. 

104.  Glaciation  of  the  Yellowstone  Valley  north  of  the  Park,  liy  Walter  Harvey  AVeetl.    1893.    8°. 
41  pp.     4  pi.     Price  5  cents. 

105.  The  Laramie  and  the  Overlying  Livingstone  Formation  in  Montana,  hy  AValter  Harvey 
Weed,  with  Report  on  Flora,  by  Frank  Hall  Knowlton.     1893.     8^.     68  pp.     6  pi.     Price  10  ceuts. 

106.  The  Colorado  Formation  and  its  Invertebrate  Fauua,  by  T.  W.  Stanton.     1893.     8-^.     288 
pp.     45  pi.     Price  20  ceuts. 

107.  The  Trap  Dikes  of  the  Lake  Champlain  Region,  by  James  Furman  Kemp  and  Vernon 
Freeman  Marsters.     1893.     8^.     62  pp.     4  pi.     Price  10  ceuts. 

108.  A  Geological  Eecounoissance  in  Central  Washington,  by  Israel  Cook  Russell.     1893.     8". 
108  pp.     12  pi.     Price  15  ceuts. 

109.  The  Eruptive  and  Sedimeutary  Rocks  on  Pigeon  Point,  Minnesota,  and  their  Contact  Phe- 
nomena, by  William  Shirley  Bay  ley.     1893.     8°.     121  pp.     16  pi.     Price  15  cents. 

110.  The  Paleozoic  Section  in  the  Vicinity  of  Three  Forks,  Montana,  by  Albert  Charles  Peale. 
893.     8°.    56  pp.     6  pi.     Price  10  ceuts. 

111.  Geology  of  the  Big  Stone  Gap  Coal  Fields  of  Virginia  and  Kentucky,  by  Marius  R.  Camp- 
bell.    1893.     8°.     106  pp.     6  pi.     Price  15  cents. 

112.  Earthquakes  in  California  iu  1892,  by  Charles  D.Perrine.    1893.    8^.    57  pp.    Price  10  cents. 

113.  A  Report  of  Work  done  in  the  Division  of  Chemistrv  during  the  Fiscal  Years  1891-''92  and 
1892-'93.     F.  W.  Clarke,  Chief  Chemist.     1893.     8^=.     115  pp.     Price  15  cents. 

114.  Earthciuakes  in  California  in  1893,  by  Charles  D.  Perrine.    1894.    8^^.    23  pp.    Price  5  cents. 

115.  A  Geographic  Dictionary  of  Rhode  Island,  by  Henry  Gannett.     1894.     8°.     31  pp.     Price 
5  cents. 

116.  A  Geographic  Dictionary  of  Massachusetts,  by  Henry  C4annett.     1894.     8°.     126  pp.     Price 
15  cents. 

117.  A  Geographic  Dictionary  of  Connecticut,  by  Henry  Gannett.     1894.     8°.     67  pp.     Price  10 
cents. 

118.  A  Geographic  Dictionary  of  New  Jersey,  by  Henry  Gannett.     1894.     8°.     131  pp.     Price  15 
cents. 

119.  A  Geological  Reconnoissance  iu  Northwest  Wyoming,  by  George  Homans  Eldridge.     1894. 
8°.     72  pp.     Price  10  cents. 

120.  The  Devonian  System  of  Eastern  Pennyslvauia  and  New  York,  by  Charles  S.  Prosser.     1894. 
8^.     81pp.     2  pi.     Price  10  cents. 

121.  A  Bibliography  of  North  American  Paleontology,  by  Charles  Rollin  Keyes.     1894.    8^.     251 
pp.     Price  20  cents. 

122.  Results  of  Primary  Triangulatiou,  by  Henry  Gannett.     1894.     8°.     412  pp.     17  pi.     Price 
25  cents. 

123.  A  Dictionary  of  Geographic  Positions,  by  Henry  Gannett.     1895.     8°.     183  pp.     1  pi.    Price 
15  cents. 

124.  Revision  of  North  American  Fossil  Cockroaches,  by  Samuel  Hubbard  Scudder.     1895.     8'^. 
176  pp.     12  pi.     Price  15  cents. 

125.  The  Constitution  of   the   Silicates,  by  Frank  Wigglesworth  Clarke.     1895.     8=.     109   pp.  ' 
Price  15  cents. 

126.  A  Mineralogical  Lexicon  of  Franklin,  Hampshire,  and  Hampden  couuties,  Massachusetts, 
by  Benjamin  Kendall  Emerson.     1895.     8°.     180  pp.     1  pi.     Price  15  cents. 

127.  Catalogue  aud  Index  of  Contributions  to  North  American  Geology,  1732-1891,  by  Nelson 
Horatio  Darton.     1896.     8^.     1045  pp.     Price  60  cents. 

128.  The  Bear  River  Formation  aud  its  Characteristic  Fauna,  by  Charles  A.  White.     1895.     8°. 
108  pp.     11  pi.     Price  15  cents. 

129.  Earthquakes  in  California  iu  1894,  by  Charles  D.  Perrine.    1895.     8°.     25  pp.     Price  5  ceuts. 

130.  Bibliography  and  Index  of  North  American  Geology,  Paleontology,  Petrology,  and  Miner- 
alogy for  1892  and  1893,  by  Fred  Boughton  Weeks.     1896.     8^.     210  pp.     Price  20  cents. 

131.  Report  of  Progress  of  the  Division  of  Hydrography  for  the  Calendar  Years  1893  and  1894, 
by  Frederick  Hayues  Newell,  Topographer  iu  Charge.     1895.     8-.     126  pp.     Price  15  cents. 

132.  The  Disseminated  Lead  Ores  of  Southeastern  Missouri,  by  Arthur  Winslow.     1896.     8°. 
31  pp.     Price  5  cents. 

133.  Contributions  to  the  Cretaceous  Paleontology  of  the  Pacific  Coast:    The  Fauna  of  the 
Kuoxville  Beds,  by  T.  W.  Stanton .     1895.    8°.     132  pp.     20  pi.     Price  15  cents. 

134.  The  Cambrian  Rocks  of  Pennsylvania,  by  Charles  Doolittle  Waloott.     1896.     8^.     43  pp. 
15  pi.     Price  5  cents. 

135.  Bibliography  and  Index  of  North  American  Geology,  Paleontology,  Petrology,  and  Miner- 
alogy for  the  Year  1894,  by  F.  B.  AVeeks.     1896.     8°.     141  pp.     Price  15  cents. 

136.  Volcanic  Rocks  of  South  Mountain,  Pennsylvania,  by  Florence  Bascom.    1896.    8^.    124  pp. 
28  pi.     Price  15  cents. 

137.  The  Geology  of  the  Fort  Riley  Military  Reservation  aud  Vicinity,  Kansas,  by  Robert  Hay. 
1896.     8^.     35  pp.     8  pi.     Price  5  cents. 

138.  Artesian-Well  Prospects  in  the  Atlantic  Coastal  Plain  Region,  by  N.  H.  Darton.     1896.     8°. 
228  pp.     19  pi.     Price  20  cents. 

139.  Geology  of  the  Castle  Mountain  Mining  District,  Montana,  by  W.  H.  Weed  and  L.  V.  Pirs- 
son.     1896.     8°.     164  pp.     17  pi.     Price  15  cents. 

140.  Report  of  Progress  of  the  Division  of  Hydrography  for  the  Calendar  Year  1895,  by  Frederick 
Haynes  Newell,  Hydrographer  in  Charge.     1896.     S"^.     3.56  pp.     Price  25  cents. 


ADVERTISEMENT.  VII 

141.  The  Eocene  Deposits  of  the  Middle  Atlantic  Slope  in  Delaware,  Maryland,  and  Virginia, 
by  William  Bnllocli  Clark.     1896.     8°.     167  pp.     40  pi.     Price  15  cents. 

142.  A  Brief  Contribution  to  the  Geology  and  Paleoutology  of  Northwestern  Louisiana,  by 
T.  Wayland  Vaughan.     1896.     8°.     65  pp.     i  pi.     Price  10  cents. 

143.  A  Bibliography  of  Clays  and  the  Ceramic  Arts,  by  John  C.  Branner.  1896.  8".  114  pp. 
Price  15  cents. 

144.  The  Moraines  of  the  Missouri  Coteau  and  their  Attendant  Deposits,  by  James  Edward  Todd. 
1896.     8-^.     71  pp.     21  pi.     Price  10  cents. 

145.  The  Potomac  Formation  in  Virginia,  by  W.  M.  Fontaine.  1896.  8^.  149  pp.  2  pi.  Price 
15  cents. 

146.  Bibliography  and  Index  of  North  American  Geology,  Paleoutology,  Petrology,  and  Miner- 
alogy for  the  Year  1895,  by  F.  B.  Weeks.     1896.     »\     130  pp.     Price  15  cents. 

147.  Earthquakes  in  California  in  1895,  by  Charles  D.  Perrine,  Assistant  Astronomer  in  Chargo 
of  Earthquake  Observations  at  the  Lick  Observatory.     1896.     8^\     23  i^p.     Price  5  cents. 

148.  Analyses  of  Eoeks,  with  a  Chai^ter  on  Analytical  Methods,  Laboratory  of  the  United  States 
Geological  Survey,  1880  to  1896,  by  F.  W.  Clarke  and  W.  F.  Hillebrand.  1897.  8-^.  306  pp.  Price 
20  cents. 

149.  Bibliography  and  Index  of  North  American  Geology,  Paleontology,  Petrology,  and  Miner- 
alogy for  the  Year  1896,  by  Fred  Bough  ton  Weeks.     1897.     8°.     152  pp.     Price  15  cents.  ' 

150.  The  Educational  Series  of  Eock  Specimens  collected  and  distributed  by  the  United  States 
Geological  Survey,  by  Joseph  Silas  Diller.     1898.    8^.     398  pp.     47  pi.     Price  25  cents. 

151.  The  Lower  Cretaceous  Gryphfeas  of  the  Texas  Kegion,  by  E.  T.  Hill  and  T.  Wayland 
Vaughan.     1898.     »''-'.     139  pp.     25  pi.     Price  15  cents. 

152.  A  Catalogue  of  tbe  Cretaceous  and  Tertiary  Plants  of  North  America,  by  F.  H.  Knowlton. 
1898.     8=.     247  pp.     Price  20  cents. 

153.  A  Bibliographic  Index  of  North  American  Carboniferous  Invertebrates,  by  Stuart  Weller. 
1898.     8°.     653  pp.     Price  35  cents. 

154.  A  Gazetteer  of  Kansas,  by  Henry  Gannett.     1898.     8°.     246  pp.     6  pi.     Price  20  cents. 

155.  Earthquakes  in  California  in  1896  and  1897,  by  Charles  D.  Perrine,  Assistant  Astronomer 
in  Charge  of  Earthquake  Observations  at  the  Lick  Observatory.     1898.    8°.     47  pp.     Price  5  cents. 

156.  Bibliography  and  Index  of  North  American  Geology,  Paleontology,  Petrology,  and  Miner- 
alogy for  the  Year  1897,  by  Fred  Boughtou  Weeks.     1898.     8"^.     130  pp.     Price  15  cents. 

160.  A  Dictionary  of  Altitudes  in  the  United  States  (Third  Edition),  compiled  by  Henry 
Gannett.     1899.     8-^.     775  pp.     Price  40  cents. 

161.  Earthquakes  In  California  in  1898,  by  Charles  D.  Perrine,  Assistant  Astronomer  in  Charge 
of  Earthquake  Observations  at  the  Lick  Observatory.     1899.     8°.     31pp.     1  pi.     Price  5  cents. 

In  preparation: 

157.  The  Gneisses,  Gabbro-Schists,  and  Associated  Socks  of  Southeastern  Minnesota,  by  C.  W. 
Hall. 

158.  The  Moraines  of  southeastern  South  Dakota  and  their  Attendant  Deposits,  by  J.  E.  Todd. 

159.  The  Geology  of  Eastern  Berkshire  County,  Massachusetts,  by  B.  K.  Emerson. 

WATER-SUPPLY  AND  IRRIGATION  PAPERS. 

By  act  of  Congress  approved  June  11,  1896,  the  following-  provision  was  made: 
"Provided,  That  hereafter  the  reports  of  the  Geolo.-ical  Survey  in  relation  to  the  gauging  of 
streams  and  to  the  methods  of  utilizing  the  water  resources  may  be  prln'ed  in  octavo  form,  not  to 
exceed  one  hundred  pages  in  length  and  five  thousand  copies  in  number;  one  thousand  copies  of  which 
shall  be  for  the  oBicial  use  of  the  Geological  Survey,  one  thousand  five  hundred  copies  shall  be  deliv- 
ered to  the  Senate,  and  two  thousand  five  hundred  copies  .shall  be  delivered  to  the  House  of  Repre- 
sentatives, for  distribution." 

Under  this  law  the  following  papers  have  been  issued : 

1.  Pumping  Water  for  Irrigation,  by  Herbert  M.  Wilson.     1896.     8'^.     57  pp.     9  pi. 

2.  Irrigation  near  Phcenix,  Arizona,  by  Arthur  P.  Davis.     1897.     8°.    97  pp.     3l'pl. 

3.  Sewage  Irrigation,  by  George  W.  Rafter.     1897.     8'^.     100  pp.     4  pi. 

4.  A Eeconnoissance  in  Southeastern  Washington,  by  Israel  Cook  Russell.    1897.    8°.    96  pp.    7  pi. 

5.  Irrigation  Practice  on  the  Great  Plains,  by  Elias  Branson  C'owgill.     1897.     8°.     39  pp.     12  pi. 

6.  Underground  Waters  of  Southwestern  Kansas,  by  Erasmus  Haworth.    1897.    8^.    65  pp.    12  pi. 

7.  Seepage  Waters' of  Northern  Utah,  by  Samuel  Fortier.     1897.     8°.     50  pp.     3  pi. 

8.  Windmills  for  Irrigation,  by  Edward  Charles  Murphy.     1897.     8<^.     49  pp.    8  pi. 
9..  Irrigation  near  Greeley,  Colorado,  by  David  Boyd.     1897.     8'-.     90  pp.    21  pi. 

10.  Irrigation  in  Mesilla  Valley,  New  Mexico,  by  F.  C.  Barker.     1898.     8'-.     51  pp.     11  pi. 

11.  River  Heights  for  1896,  by  Arthur  P.  Davis.     1897.     8°.     100  pp. 

12.  Water  Resources  of  Southeastern  Nebraska,  by  Nelson  H.  Darton.     1898.     8^.     .55  pp.     21  pi. 

13.  Irrigation  Systems  in  Texas,  by  William  Ferguson  Hutson.     1898.     S"-"".     67  pp.     10  pi. 

14.  New  Tests  of  Certain  Pumps  and  Water-Lifts  used  in  Irrigation,  by  Ozni  P.  Hood.  1889.  8°. 
91pp.     1  pi. 

15.  Operations  at  River  Stations,  1897,  Part  I.     1898.     8^=.     100  pp. 

16.  Operations  at  River  Stations,  1897,  Part  II.     1898.     8^\     101-200  pp. 

17.  Irrigation  near  Bakersfield,  California,  by  C.  E.  Grunsky.     1898.     8-.     96  pp.     16  pi. 

18.  Irrigation  near  Fresno,  California,  by  C.  E.  Grunsky.     1898.     8°.     94  pp.     14  pi. 

19.  Irrigation  near  Merced,  California,  by  C.  E.  Grunsky.     1899,     8°.     59  pp.     11  pi. 

20.  Experiments  with  Windmills,  by  T.  0.  Perry.     1899.     8-.     97  pp.     12  pi. 


VIII 


ADVERTISEMENT. 


21.  Wells  of  Northern  Indiana,  by  Frank  Leverett.      1899.     8^.     82  pp.     2  pi. 

22.  Sewage  Irrig.ation,  Part  II,  by  George  W.  Kalter.     1899.     8-.     100  pp.     7  pi. 

23.  Water-Eight  Problems  of  Bighorn  Monntains,  by  Elwoocl  Mead.     1899.     8°.     62  pp.     7  pi. 

24.  Water  Resources  of  the  State  of  New  York,  Part  I,  by  George  W.  Rafter.  1899.  8°. 
99  pp.     13  pi. 

25.  AVater  Resources  of  the  State  of  New  York,  Part  II,  by  George  W.  Rafter.  1899.  8-. 
101-200  pp.     12  pi. 

26.  Wells  of  Southern  Indiana  (Continuation  of  No.  21),  by  Frank  Leverett.     1899.     8^\     64  pp. 

27.  Operations  at  River  Stations,  1898,  Part  I.     1899.     8°.     100  pp. 

28.  Operations  at  River  Stations,  1898,  Part  II.     1899.     8^.     101-200  pp. 

In  pre2)aration: 

29.  Wells  and  Windmills  in  Nebraska,  by  Edwin  H.  Barbour. 

30.  Water  Resources  of  the  Lower  Peninsula  of  Michigan,  by  Alfred  C.  Lane. 

TOPOGRAPHIC  MAP  OF  THE  UNITED  STATES. 

When,  in  1882,  the  Geological  Survey  was  directed  by  law  to  make  a  geologic  map  of  the  United 
States  there  was  in  existence  no  suitable  topographic  map  to  serve  as  a  base  for  the  geologic  map. 
The  preparation  of  such  a  topographic  map  was  therefore  immediately  begun.  About  one-fifth  of  the 
area  of  the  country,  excluding  Alaska,  has  now  been  thus  mapped.  The  map  is  published  in  atlas 
sheets,  each  sheet  rejiresenting  a  small  quadrangular  district,  as  explained  under  the  next  head- 
ing. The  separate  sheets  are  sold  at  5  cents  each  when  fewer  than  100  copies  are  purchased,  but  when 
they  are  ordered  in  lots  of  100  or  more  copies,  whether  of  the  same  sheet  or  of  dift'erent  sheets,  the 
price  is  2  cents  each.  The  mapped  areas  are  widely  scattered,  nearly  every  State  being  represented. 
About  900  sheets  have  been  engraved  and  printed;  they  are  tabulated  by  States  in  the  Survey's 
"List  of  Publications,"  a  pamphlet  which  may  be  had  on  application. 

The  map  sheets  represent  a  great  variety  of  topographic  features,  and  with  the  aid  of  descriptive 
text  they  can  be  used  to  illustrate  topographic  forms.  This  has  led  to  the  projection  of  an  educational 
series  of  topographic  folios,  for  use  wherever  geography  is  taught  in  high  schools,  academies,  and 
colleges.     Of  this  series  the  first  folio  has  been  issued,  viz : 

1.  Physiographic  types,  by  Henry  Gannett,  1898,  folio,  consisting  of  the  following  sheets  and  4 
pages  of  descriptive  test:  Fargo  (N.  Dak.-Miun.),  a  region  in  youth  ;  Charleston  (W.Va.),a  region  in 
maturity;  Caldwell  (Kans.),  aregion  in  old  age;  Palmyra  (Va.),  a  rejuvenated  region;  Mount  Shasta, 
(C'al.),  a  young  volcanic  mountain ;  Eagle  (Wis.),  moraines;  Sun  Prairie  (Wis.),  drumlius;  Donald- 
sonville  (La.),  river  flood  plains;  Boothbay  (Me.),  a  fiord  coast;  Atlantic  City  (N.  J.),  a  barrier-beach 
coast. 

GEOLOGIC  ATLAS  OF  THE  UNITED  STATES. 

The  Geologic  Atlas  of  the  United  States  is  the  final  form  of  publication  of  the  topographic  and 
geologic  maps.  The  atlas  is  issued  in  parts,  progressively  as  the  surveys  are  extended,  and  is  designed 
ultimately  to  cover  the  entire  country. 

Under  the  plan  adopted  the  entire  area  of  the  country  is  divided  into  small  rectangular  districts 
(designated  quadrangles),  bounded  by  certain  meridians  and  jiarallels.  The  unit  of  survey  is  also  the 
unit  of  publication,  and  the  maps  and  descriptions  of  each  rectangular  district  are  issued  as  a  folio  of 
the  Geologic  Atlas. 

Each  folio  contains  topographic,  geologic,  economic,  and  structural  maps,  together  with  textual 
descriptions  and  explanations,  and  is  designated  by  the  name  of  a  principal  town  or  of  a  prominent 
natural  feature  within  the  district. 

Two  forms  of  issue  have  been  adoi>ted,  a  "library  edition"  and  a  "field  edition."  In  both  the 
sheets  are  bound  between  heavy  paper  covers,  but  the  library  copies  are  permanently  bound,  while 
the  sheets  and  covers  of  the  field  copies  are  only  temporarily  wired  together. 

Under  tlie  law  a  copy  of  each  folio  is  sent  to  certain  public  libraries  and  educational  institu- 
tions. The  remainder  are  sold  at  25  cents  each,  except  such  as  contain  an  unusual  amount  of  matter, 
which  are  priced  accordingly.  Prepayment  is  obligatory.  The  folios  ready  for  distribution  are  listed 
below. 


No. 

Niirae  of  sheet. 

State. 

Limiting  meridians. 

Limiting  parallels. 

Area,  in 
square 
miles. 

Price, 

in 
cents. 

Montana 

110°-lllo 

}                           850-85°  30' 

120°  30'-121° 

8  to  30'-85° 

1210-121°  30' 

850--850  30' 

1050-105°  30' 

85°  30'-86o 

106°  45'-107o  15' 

I                           77°  30'-78o 

450-46° 
34°  30'-35° 
380  30'-39o 
350  30-36° 
38°  30'-39o 
35°-85o  30' 
38°  30'-39o 
350-350  30' 
38°  45'-39o 

390-39°  30' 

3,354 
980 
932 
969 
932 
975 
932 
975 
465 

925 

25 

\Tennessee 

California 

Tennessee 

California 

Tennessee 

Colorado 

Tennessee 

Colorado 

[Virginia 

i  West  Virginia . . 
(Maryland 

25 

25 

25 

fi 

25 

7 

R 

Pikes  Peak  (out  of  stock) 

25 
25 

9 

in 

Anthracite-Crested  Butte 

50 
25 

ADVERTISEMENT. 


Limiting  meridians. 


Limiting  parallels. 


Area,  in  'Price, 
square   |    in 
miles,    'cents. 


Fredericksburg 


Lassen  Peak. 
Knoxville 


Stevenson  . 


California 

(Virginia 

•|  Kentucky 

(Tennessee 

(Maryland 

:\Virginia 

/Virginia 

I. West  Virginia. 

California 

(Tenoeasee 

|.North  Carolina 

California 

California 

("Alabama 

<  Georgia 

(Tennessee 

Tennessee 

Tennessee 

Tennessee 


Nevada  City. 


"Wyoming 


California  , 
/Virginia , 


tWeat  Virginia . . 
T< 


Tazewell 

Eoise 

Kichraond 

London 

Teumile  District  Special 

Koseburg 

Hoi  yoke 


California  . 


Cleveland '. 

Pikeville 

McMinnville 

^-™ n^;^ 

Three  Forks Montana 

Loudon j  Tennessee 

Ponlinntn^  l/Virginia 

J-ocanortaa 1  West  Virginia . . 

Horriatown Tennessee 

(Virginia 

Piedmont I  Maryland 

["West  Virginia.. 

[Nevada  City. 

^  Grass  Valley. 

iBanner  Hill  . 

fGallatin.. 

Yellowstone    Nsl-  J  Cany  on... 

,    tionalPark.         ]  Shoshone  . 

[Lake 

Pyramid  Peak 

Franklin 

Briceville 

Buckhannon 

Gadsden 

Pueblo 

Do\TBievilIe 

Butte  Special 

Truckee 

"Wartburg 

SoDora 

Nueces 

BidwellBar 


121°  00' 
121°  01' 
.120°  57' 


West  Virginia . 

Alabama 

Colorado 

California 

Montana 

California 

Tennessee 

California 

Texas 

California 

rVirginia 

^West  Virginia. 

Idaho 

Kentucky 

Kentucky 

Colorado 

Oregon 

/Massachusetts 
IConnecticut  ... 


120°  30'-121o 
82°  30'-83° 


79°-79°  30' 

121°-122° 

63°  30'-84° 


84°  30'-85° 
85°-8o°  30' 
85°  30'-86o 


81°-81°  30' 
83°-S3°  30' 


-121°  03'  45" 
-121°  05'  04" 
-121°  00'  25" 


120°-120°  30' 

79°-79o  30' 

840-84°  30' 

80°-80°  30' 

86°-86o  30' 

104°  30'-105° 

120°  30'-121° 

30"-112°  36'  42" 

1200-120°  30' 

84°  30'-85° 

1200-120°  30' 

100°-100o  30' 

121°-121°  30' 

81°  30'-82o 

1160-116°  30' 

84°-84°  30' 

840-84°  30' 

106O  8'-106°  16' 

123°-123°  30' 

72°  30'-73o 


380-38°  30' 

40°-41o 

35°  30'-36° 


35°-350  30' 
35°  30'-36o 
35°  30'-36o 


37°-37°  30' 
36°-36o  30' 


'  13'  50"-39°  17'  16" 
'  10'  22"-39°  13'  60" 
'  13'  50"-39o  17'  16" 


38°  30'-39° 
360-36°  30' 
38°  30'-39° 
34°-34°  30' 
380-38°  30' 
390  30'-40° 

450  59'  28"-46°  02'  54" 
39°-39°  30' 
36°-36°  30' 
370  30'-38o 
290  30'-30° 
39°  30'-40o 
37°-37o  30' 
430  30'-44o 
370  30'-38o 
370-370  30' 

390  22'  30"-39°  30'  30" 
43°-43°  30' 
42°-42o  30' 


11.65 
12.09 
11.65 


STATISTICAL  PAPERS. 


Mineral  Resources  of  the  United  States  [1882],  by  Albert  Williams,  jr.  1883.  8^.  xvii,  813  pp. 
Price  50  cents. 

Mineral  Resources  of  the  United  States,  1888  and  1884,  by  Albert  Williams,  jr.  1885.  8^.  xiv, 
1016  pp.     Price  60  cents. 

Mineral  Resources  of  the  United  States,  1885.  Division  of  Mining  Statistics  and  Technology. 
1886.     8°.     vil,  576  pp.     Price  40  cents. 

Mineral  Resources  of  the  United  States,  1886,  by  David  T.  Day.  1887.  8°.  viii,  813  pp.  Price 
60  cents. 

Mineral  Resources  of  the  United  States,  1887,  by  David  T.  Day.  1888.  8°.  vii,  882  pp.  Price 
50  cents. 

Mineral  Resources  of  the  United  States,  1888,  by  David  T.  Day.  1890.  8^.  vii,  652  pp.  Price 
50  cents. 

Mineral  Resources  of  the  United  States,  1889  and  1890,  by  David  T.  Day.  1892.  8°.  viii,  671pp. 
Price  50  cents. 

Mineral  Resources  of  the  United  States,  1891,  by  David  T.  Day.  1893.  8^.  vii,  630  pp.  Price 
50  cents. 


X  ADVERTISEMENT. 

Mineral  Resources  of  the  United  States,  1892,  Ijy  Davicl  T.  Day.  1893.  8  =  .  vii,  850  pp.  Price 
50  cents. 

Mineral  Resources  of  the  United  States,  1893,  by  David  T.  Day.  1894.  8".  viii,  810  pp.  Price 
50  cents. 

On  March  2, 1895,  the  following  provision  Tras  included  iu  an  act  of  Congress : 

"Provided,  That  hereafter  the  report  of  the  mineral  resources  of  the  United  States  shall  be 
issued  as  a  part  of  the  rei>ort  of  the  Director  of  the  Geological  Survey." 

In  compliance  with  this  legislation  the  following  reports  have  been  published : 

Mineral  Resources  of  the  United  States,  1894,  David  T.  Day,  Chief  of  Division.  1895.  8^.  xv, 
646  pp.,  23  pi. ;  xix,  735  pp.,  6  pi.     Being  Parts  III  and  IV  of  the  Sixteenth  Annual  Report. 

Mineral  Resources  of  the  United  States,  1895,  David  T.  Day,  Chief  of  Division.  1896.  8°. 
xxiii,  542  pp.,  8  pi.  and  maps;  iii,  543-1058  pp.,  9-13  pi.  Being  Part  III  (in  2  vols.)  of  the  Seventeenth 
Annual  Report. 

Mineral  Resources  of  the  United  States,  1896,  David  T.  Day,  Chief  of  Division.  1897.  8-'. 
xii,  642  pp.,  1  pi. ;  643-1400  pp.     Being  Part  V  (in  2  vols.)  of  the  Nineteenth  Annual  Report. 

Mineral  Resources  of  the  United  States,  1897,  David  T.  Day,  Chief  of  Division.  1898.  8^. 
viii,  651  pp.,  11  pi. ;  viii,  706  pp.     Being  Part  VI  (in  2  vols.)  of  the  Nineteenth  Annual  Report. 

The  money  received  from  the  sale  of  the  Survey  publications  is  deposited  in  the  Treasury,  and 
the  Secretary  of  that  Department  declines  to  receive  bank  checks,  drafts,  or  postage  stamps;  all  remit- 
tances, therefore,  must  be  by  money  order,  made  payable  to  tlie  Director  of  the  United  States 
Geological  Survey,  or  in  currency — the  exact  amount.  Correspondence  relating  to  the  publications 
of  the  Survey  should  b,e  addressed  to 

The  Director, 

United  States  Geological  Survey, 
Washington,  D.  C,  June,  1S99.  Washington,  D.  C. 


[Take  this  leaf  out  and  paste  the  separated  titles  upon  three  of  your  cata- 
logue cards.  The  first  aud  second  titles  need  no  addition ;  over  the  third  "write 
that  subject  under  which  you  would  place  the  book  in  your  library.] 


LIBRARY  CATALOGUE  SLIPS. 

United  States.     Departmeni  of  the  interior.     {V,  S.  geological  survey.) 
Department  of  the  interior  |  —  |  Monographs  |  of  the  |  United 
States  geological  survey  |  Volume  XXXIV  |  [Seal  of  the  depart- 
ment] I 
Washington  |  government  printing  office  |  1899 
Second    title:   United    States  geological   survey   |  Charles   D. 
AValcott,  director  |  —  |  The  |  glacial  gravels   of  Maine  |  and  | 
their  associated  deposits  |  by  |  George  H.  Stone  |  [Vignette]  | 
"Washington  |  government  printing  oflice  |  1899 
4°.    xiii,  499  pp.    52  pi. 


Stone  (George  H.) 

United  States  geological  survey  |  Charles  D.  Walcott,  di- 
rector I  —  I  The  I  glacial  gravels  of  Maine  |  and  |  their  associated 
deposits  I  by  |  George  H.  Stone  |  [Vignette]  | 

"Washington  |  government  printing  office  |  1899 

i^.    xiii,  499  pp.    52  pi. 

[United  States.  Department  of  the  mtenor.  (TT.  S.  geological  survey.) 
Monograph  XXXIT.] 


United  States  geological  survey  |  Charles  D.  Walcott,  di- 
rector I  —  I  The  I  glacial  gravels  of  Maine  |  and  |  their  associated 
deposits  I  by  |  George  H.  Stone  |  [Vignette]  | 

Washington  |  government  printing  office  |  1899 

4°.    xiii,  499  pp.     52  pi. 

[United  States.  Department  of  the  interior.  (U.  S.  geological  survey. 
Monograph  XXSIV.] 


